## Remote Interior Angles: Definition & Examples – Video & Lesson Transcript

To begin, let’s examine what we already know about triangles before moving on to additional instances. As previously established, the sum of the three interior angles of a triangle equals 180 degrees. In addition, you may recall that when you lengthen the line of a triangle, you not only produce an outside angle, but you also make a straight line. The length of a straight line is also 180°, hence the total of both the exterior angle and neighboring angle (the angle next to the exterior angle) is likewise 180°.

### Example1

Let’s try to assist Rachel in determining the unknown angle,y, in the following illustration: In order to begin, we must first determine the interior and external angles. The outer angle would be 45 degrees, while the inside angles would be 30 degrees, 135 degrees, and angley. We may utilize distant interior angles to solve for the unknown angle by using remote interior angles. As far as we are aware, the following is correct: 45° = angley + 30° = 45° As a result, angley= 15°. We can double-check this answer because we know that the sum of the three interior angles of a triangle must equal 180 degrees.

### Example2

Let’s help Rachel go through another situation in which we don’t know what the external aspect is going to be like.

## Remote Interior Angles – Concept – Geometry Video by Brightstorm

When one side of a triangle is stretched beyond the point of intersection, anexterior angle is created. This outer angle is additional to the linear angle that is immediately adjacent to it. Due to the fact that the sum of the angles in a triangle is likewise 180 degrees, the exterior angle must have a measure equal to the sum of the remaining angles, which are referred to as the remote interior angles. We should consider what they mean in English when we talk about external angles and remote interior angles, because this will help us understand what we are talking about.

- The angles that are inside the triangles are called the interior angles, while the angles that are outside the triangles are called the distant angles.
- The remote interior angles are 3 and 4, so 1 is your exterior angle because it’s outside, and the two angles that aren’t adjacent to 1 are your remote interior angles, as is the case with the remote exterior angles.
- McCall, you need to prove that,” so what I’m going to do is say that angle 1 and angle 2 must sum to 180 degrees because if I add those two angles together, we get a straight line; so what I’m going to do is say that angle 1 and angle 2 must sum to 180 degrees.
- Because they form a triangle, the numbers 2, 3, and 4 must add up to 180 degrees.
- Since I already have 180 degrees on both sides, I’ll just subtract 180 degrees from both sides and that will make them disappear.

## Exterior Angle Theorem – Explanation & Examples

In other words, we all understand that a triangle is a three-sided shape with three inner angles. However, there are additional angles that occur outside of the triangle, which are referred to as external angles. Knowing that the total of all three internal angles of a triangle is always equal to 180 degrees, we may use this to our advantage. This characteristic holds true for both interior and exterior angles in the same way. In addition, the inner angles of a triangle are more than zero degrees but less than 180 degrees on each side.

We will learn about the following topics in this article:

- Interior angles of a triangle, as well as how to find the unknown exterior angle of a triangle, are all covered in this chapter.

## What is the Exterior Angle of a Triangle?

It is the angle created between one side of a triangle and the extension of its neighboring side that is known as the external angle of a triangle. The internal angles of the triangle ABC are denoted by the letters a, b, and c, while the outer angles are denoted by the letters d, e, and f. Supplementary angles are those that are next to each other on the inside and outside of the building. In other words, the total of each inner angle and its neighboring exterior angle is equal to 180 degrees when the interior angles are added together (straight line).

## Triangle Exterior Angle Theorem

The exterior angle theorem asserts that the measure of each exterior angle of a triangle is equal to the sum of the measures of the opposing and non-adjacent interior angles of the triangle in question. It’s important to remember that the two non-adjacent interior angles on each side of the exterior angle are referred to as distant interior angles in some cases. For example, in the triangleABCabove, d = b + a, e = a + c, and f = b + c, respectively. Angles on the outside have certain characteristics.

- When a triangle has two opposed interior angles, its exterior angle is the sum of the two opposite interior angles. One hundred and eighty degrees is equal to the sum of the outer angle and the inner angle.

C + D = 180°A + F = 180°B + E = 180°C + D + a = 180°B + E = 180° Proof: d + e + f = b + a + a + c + b + c d +e + f = 2a + 2b + 2c= 2(a + b + c) d +e + f = 2a + 2b + 2c= 2(a + b + c) However, according to the triangle angle sum theorem, the angles a, b, and c equal 180 degrees. As a result, d + e + f = 2(180°)= 360° for d + e + f.

## How to Find the Exterior Angles of a Triangle?

The methods for determining the outer angles of a triangle are quite similar to the rules for determining the internal angles of a triangle. This is due to the fact that wherever there is an external angle, there is also an internal angle associated with it, and the sum of the two angles equals 180 degrees. Examine a few real-world problems as illustrations. Exemple No. 1 Assuming that the inner angles 25° and (x + 15) ° of a triangle are non-adjacent to the exterior angle (3x – 10) °, calculate what the value of the variable is.

- (x+15) = (25 + 15) ° = 40° (3x 10) = 3(25°) – 10°= (75 – 10) ° = 65° (3x 10) = 3(25°) – 10°= (75 – 10) ° = 65° (3x 10) = 3(25°) – 10°= (75 – 10) ° = 65° (3x 10) = 3(25°) – 10°= (75 – As a result, the angles are 25 degrees, 40 degrees, and 65 degrees.
- 2 Calculate the values ofx and y in the triangle shown below.
- As a result of the Triangle exterior angle theorem.
- As a result, we have: y + x = 180° 140° + y = 180° deduct 140° from both sides of the equation 120 – 140 = 40 y = 180° – 140°y As a result, the values of x and y are 140 degrees and 40 degrees, respectively.
- Find the value of x if the non-adjacent interior angles of the two opposing non-adjacent interior angles are (4x + 40)° and 60°.
- 120° = 4x + 40 + 60 = 240° Simplify.
- 120° – 100° = 4x + 100° – 100° 20° = 4x + 120° – 100° = 4x x = 5° is obtained by dividing both sides by.
- Substituting the correct answer will verify the answer.
- 4 Image out what the values of x and y are in the figure below.
- Simplify.

Take 133° off both sides of the equation. 45 degrees from the origin (y = 180 – 133 degrees) and 47 degrees from the origin. Use the triangle exterior angle theorem to solve your problem. the angle x = 41° plus 47°x = 88° This results in x and y having values of 88.5 and 47 degrees, respectively.

## How do you find remote interior angles?

0:123:02 Interior Views from a Distance – YouTube YouTube the beginning of the proposed clip the end of the suggested clip This is angle one outside of our triangle; the angles that are within the triangles are the other angles. As a result, this is the first angle outside our triangle. The internal angles of triangles are those that are contained within the triangles. However, there are only two that our remote can control.

### What are the remote interior angles of a triangle?

The interior angles of a triangle that are not contiguous to a specific angle are referred to as remote internal angles. 6th Illustration: In the illustration below, CBD is an external view of ABC. A and C are distant interior angles on the x-axis.

### Do remote interior angles add up to 180?

The angles that are inside the triangles are called the interior angles, while the angles that are outside the triangles are called the distant angles. Because they form a triangle, the numbers 2, 3, and 4 must add up to 180 degrees.

### What are the remote interior angles of 4?

Answer: In the provided illustration, angles 1 and 2 are remote internal angles for the number 4.

### What are the remote interior angles of 3?

Examples of Remote Interior Angles in Action As previously established, the sum of the three interior angles of a triangle equals 180 degrees. In addition, you may recall that when you lengthen the line of a triangle, you not only produce an outside angle, but you also make a straight line.

### How would you compare the measure of the interior angle and its remote interior angles?

Always keep in mind that the two non-adjacent interior angles opposite the outside angle are sometimes referred to as distant interior angles since they are not contiguous to each other. An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite each other. One hundred and eighty degrees is equal to the sum of the outer angle and the inner angle.

### What are the remote interior angles to 2?

What are the angles from the outside and inside? It is possible to create an external angle in a triangle or any other polygon by extending one of the sides. In a triangle, each outside angle has two distant inside angles on the other side of the triangle. The distant interior angles are simply the two angles that are located within the triangle and are diametrically opposed to the outer angle.

### What is the sum of interior angles in a triangle?

the sum of inner angles of a 180-degree triangle

### What do same side interior angles look like?

Questions and Answers about Interior Angles on the Same Side When two parallel lines are crossed by a transversal line, the same side interior angles are generated. The same side interior angles can only be congruent if each angle is equal to 90 degrees, since the total of the same side interior angles is equal to 180 degrees when each angle is equal to 90 degrees.

### What is an example of a remote interior angle?

Internal angles that are not connected to an exterior angle by a vertex or corner of a triangle are known as remote interior angles. If angle d is considered an exterior angle, and angles a and B are considered remote internal angles of angle d, then the following is true.

### What are the remote angles of a triangle?

The distant interior angles are simply the two angles that are located within the triangle and are diametrically opposed to the outer angle.

### How are remote interior angles related to exterior angles?

An outside or external angle is formed when we stretch one of the sides of a triangle beyond its original length.

Internal angles that are not connected to an exterior angle by a vertex or corner of a triangle are referred to as remote interior angles. The measure of the external angle is the same as the sum of the two distant interior angles on each side of the angle.

### How are exterior and interior angles of a triangle related?

It all boils down to expanding one of the triangle’s sides. It is possible to create an external angle in a triangle or any other polygon by extending one of the sides. In a triangle, each outside angle has two distant inside angles on the other side of the triangle. The distant interior angles are simply the two angles that are located within the triangle and are diametrically opposed to the outer angle.

### What is the formula for exterior and interior angles?

For distant and interior angles, as illustrated in the diagram above, the formula asserts that the measure of an exterior angle is equal to the total of the remote interior angles (or vice versa). To put it another way, the angle ‘outside the triangle’ (external angle A) = D + C when the triangle is closed (the sum of the remote interior angles).

#### Related Posts:

The exterior angle theorem is found in Euclid’s Elements in Proposition 1.16, which asserts that the measure of anexterior angleof a triangleis higher than either of the measures of the distant interior angles of the triangle. This is a basic conclusion in absolute geometry since its proof does not rely on the parallel postulate, which makes it much more important. The phrase “external angle theorem” has been used to refer to a distinct conclusion in various high school geometry textbooks, notably the piece of Proposition 1.32 that asserts that the measure of an exterior angle of a triangle is equal to the sum of the measures of the distant interior angles.

Exterior angle theorems are classified into two types: strong and weak forms.

## Exterior angles

A triangle has three corners, which are referred to asvertices. Two angles are formed by the intersection of the sides of a triangle (line segments) at the vertex (four angles if you consider the sides of the triangle to be lines instead of line segments). Only one of these angles has the third side of the triangle contained inside its interior, and this angle is referred to as the interior angle of the triangle (or aninterior angle of the triangle). The three internal angles of the triangle are represented by the angles ABC, BCA, and CAB in the diagram below.

Angle ACD is an external angle depicted in the illustration.

## Euclid’s exterior angle theorem

Euclid’s proof of Proposition 1.16 is frequently cited as an example of a time when Euclid provided a faulty proof of a proposition. Euclid establishes the exterior angle theorem in the following ways:

- Make a model of the midpoint E of segment AC and draw the ray BE. Create the point F on the ray BE such that E is (also) the midway of the rays B and F
- Create the section FC by hand

By using congruent triangles, we can deduce that BAC = ECF and that ECF is smaller than ECD, and that ECD = ACD, which means that BAC is smaller than ACD. The same can be said for the angle CBA by bisecting BC, which is less than ACD. The error is in the assumption that a point (F in the example above) is “within” an angle (ACD).

Although no justification is provided for this assumption, the accompanying graphic gives the impression that it is a correct statement. A comprehensive set of axioms for Euclidean geometry (see Foundations of geometry) can be used to demonstrate the validity of Euclid’s statement.

### Invalid in Spherical geometry

In some cases, small triangles can be seen to behave in a nearly Euclidean fashion; nevertheless, the exterior angles at the base of a big triangle are 90°, which is in opposition to Euclid’s exterior angle theorem. Furthermore, the outside angle theorem does not hold true in spherical geometry, nor does it hold true in the related elliptical geometry. For example, consider the shape of a spherical triangle, one of whose vertices is located at the North Pole while the other two are located on the equator.

Because the opposite inner angle (at the North Pole) may be made bigger than 90°, this assertion is proven to be false even further.

## High school exterior angle theorem

A triangle’s exterior angle theorem (HSEAT) states that the magnitude of an exterior angle at one of a triangle’s vertices is equal to the sum of the sizes of its interior angles at the other two vertices of the triangle (remote interior angles). As a result, the size of angleAC is depicted in the illustration. AngleABC plus angleCAB = the size of angleABC + the size of angleCAB This assertion is logically analogous to the Euclidean statement that the sum of the angles of a triangle equals 180° in the HSEAT.

Creating the line parallel to sideAB is the first step in the Euclidean proof of HSEAT (and, at the same time, the result on the sum of the angles of a triangle).

## Notes

- In Henderson and Taimia 2005, p. 110
- Wylie, Jr. 1964, p. 101p. 106
- One of the line segments is designated the start side, while the other is called the terminal side. The angle is generated by moving from the starting side to the terminal side in a counterclockwise direction. Due to the arbitrary nature of the selection of which line segment would serve as the beginning side, there are two possible angles specified by the line segments: Because of this method of determining internal angles, it is not necessary to assume that the total of all the angles in a triangle equals 180 degrees
- In Faber 1983, p. 113
- Greenberg 1974, p. 99
- Venema 2006, p. 10
- In Heath 1956, Vol. 1, p. 316
- In Venema 2006, p. 10
- In Greenberg 1974, p. 99
- In Heath 1956, Vol.

## References

- Richard L. Faber’s Foundations of Euclidean and Non-Euclidean Geometry was published in 1983. Greenberg, Marvin Jay (1974), Euclidean and Non-Euclidean Geometries/Development and History, New York: Marcel Dekker, Inc., ISBN 0-8247-1748-1
- Greenberg, Marvin Jay (1974), Euclidean and Non-Euclidean Geometries/Development and History, New York: Marcel Dekker, Inc., ISBN 0-8247-1748-1
- Greenberg, Marvin Jay (19 W.H. Freeman and Company, ISBN 0-7167-0454-4
- Heath, Thomas L. San Francisco: W.H. Freeman and Company, ISBN 0-7167-0454-4
- (1956). The Thirteen Books of Euclid’s Elements are divided into three sections (2nd ed.ed.). Dover Publications, New York
- New York: Dover Publications

The following three volumes are available: ISBN0-486-60088-2 (vol. 1), ISBN0-486-60089-0 (vol. 2), and ISBN0-486-60090-4 (vol. 3). (vol. 3).

- Experiencing Geometry/Euclidean and Non-Euclidean with History, by David W. Henderson and Daina Taimia, published in 2005. (3rd ed.),
- Venema, Gerard A. (2006), Foundations of Geometry, Upper Saddle River, NJ: Pearson Prentice Hall, ISBN0-13-143700-3
- Wylie Jr., C.R. (1964), Foundations of Geometry, New York: McGraw-Hill
- Wylie Jr., C.R. (1964), Foundations of Geometry, New York

HSEAT references are provided.

- Mumbai, Maharashtra, Geometry Textbook – Standard IX Geometry Common Core, Pearson Education: Upper Saddle River, 2010
- Wheater, Carolyn C. (2007), Homework Helpers: Geometry, Franklin Lakes, NJ: Career Press, pp. 88–90, ISBN 978-1-56414-936-7
- Geometry Common Core, Pearson Education: Upper Saddle River, 2010
- Geometry Common Core, Pearson Education:

## Exterior Angle and Remote Interior Angles of a Triangle

In a triangle, the interior angle is created by the intersections of the triangle’s sides. An external angle is generated by the intersection of one side of the triangle with the extension of the opposite side of the triangle. Each exteriorangle has two distant interior angles on either side of it. An interior angle that is not contiguous to the outside angle is referred to as a distant interior angle. As seen in the diagram above,

- M1, m2, and m3 are interior angles
- M4 is an exterior angle
- M1 and m2 are remote interior angles to m4
- And m1 and m2 are remote interior angles to m4.

## Relationship Between Exterior Angle and Remote Interior Angles of a Triangle

The measurements of an external angle and its remote interior angles have a particular connection in a triangle, and this relationship is illustrated in the diagram below. Please follow the steps below to have a better understanding of this connection. Step 1:Draw a triangle and identify the angles asm1, m2, and m3 on the triangle. Step 2: Using the Triangle Sum Theorem, we havem1 + m2 + m3=180° – we havem1 + m2 + m3=180° – (1) Step 3: Extend the base of the triangle and identify the external angles with the letters m4 if necessary.

(3) Step 6: Simplify the problem by utilizing the properties of equality (3).

m1 + m2 + m3 = m3 + m4 m1 + m2 + m3 Subtract m3 from both sides of the equation. m1 plus m2 equals m4. This is referred to as the Exterior Angle Theorem, which asserts that the measure of anexteriorangle of a triangle is equal to the total of its distant interiorangles.

## Reflect

Draw a triangle and all of its outer angles on a piece of paper. 1. At each vertex of a triangle, how many exterior angles does the triangle have? 22. A triangle has a total of how many exterior angles does it have? 6 In addition to the material provided above, if you require any additional math material, please visit our Google custom search page here. Please send your comments to [email protected] if you have any. We value your comments and suggestions at all times. All intellectual property rights are retained by onlinemath4all.com.

## Exterior Angle Theorem

The interior angles of a triangle are the three anglesinsidethe triangle. |

## Exterior Angles of a Triangle

You may have guessed that exterior angles are on theoutsideof a triangle, but it’s a little more specific than just that.An exterior angle must form alinear pairwith an interior angle.This means that the exterior angle must be adjacent to an interior angle (right next to it – they must share a side) and the interior and exterior angles form a straight line (180 degrees).If you extend one of the sides of the triangle, it will form an exterior angle.There can be multiple exterior angles, it just depends on which sides of the triangle are extended.It can be tempting to think that any outside angle that touches a triangle is an exterior angle.Make sure to remember that an exterior angle must form a linear pair with an interior angle.It needs to share a side with an interior angle and the two together must form a straight line.

Here’s a non-example that could be of assistance. Angle 6 is located on the outside of the triangle, yet it is not considered an external angle by definition. However, angle 6 is not creating a linear pair with an interior angle even though it is an acute angle with an interior angle. An external angle must be located directly adjacent to an internal angle, and the two angles must share a common side (not just a vertex).

## Remote Interior Angles

It’s critical to grasp remote interior angles in order to comprehend the Exterior Angle Theorem properly. Keep in mind that internal angles are those that are on the inside of a triangle. Each outside angle has two remote interior angles on either side of it. It is the two interior angles on the inside of the triangle that are not connected to the outer angle that are referred to as distant interior angles. To think of them, think of them as the “far away” interior angles, because they are located on each side of the triangle, opposite the exterior angle.

## Finding the Measure of an Exterior Angle

It is possible to utilize the measures of the two remote interior angles in order to obtain the measure of the exterior angle if you know the measures of the two remote interior angles. Let’s pretend we have the triangle shown below and we’re attempting to figure out what x is, which is the measure of the outside angle. Every triangle has three internal angles, and we know that the sum of the three interior angles is always 180 degrees. The 64 and 45 must be added together, then the sum of the two is subtracted from 180 to obtain the missing internal angle (the one right next to the x).

The 71-degree angle that we just discovered is a linear pair with the external angle that we discovered before.

We may obtain the measure of the outside angle by subtracting 71 from the total of 180.

Take a look at the image once again.

Do you see what we could have done? It is possible to calculate the measure of the outside angle by adding the two remote interior angles together. The Exterior Angle Theorem is the name given to this shortcut since it has been demonstrated to work every time.

## The Exterior Angle Theorem

This is known as the Outside Angle Theorem, and it states that if you sum the measurements of the two remote internal angles, you will obtain the measure of the exterior angle. This theorem may be used to obtain an exterior angle more quickly than the traditional method.

## Example 1

Calculate the value of x. In this task, we’ve been provided the two distant inside angles, and we’re supposed to figure out what the two remote outside angles look like. We may apply the Exterior Angle Theorem to determine x by adding the two remote interior angles together using the Exterior Angle Theorem.

## Example 2

Calculate the value of x. It is possible to utilize the Exterior Angle Theorem to put up an equation that we will be able to solve for x using the Exterior Angle Theorem. It is necessary to add the expressions for the two remote interior angles and fix the sum to be equal to the measure of the exterior angle in order to complete the equation. Now that we’ve established an equation, we can work out what x is.

## Practice

Are you ready to experiment with a few issues on your own? To take a practice quiz, click on the START button to the right.