Test your understanding of this quick proof.

Try to answer the questions before checking the answers at the bottom of the page.

Question 1

Interior angle = 70°

Find the exterior angle.

A) 100°
B) 110°
C) 120°

Question 2

Interior angle = 60°

Find both exterior angles.

A) 100°
B) 110°
C) 120°

Question 3

Interior angle = x
Exterior angle = x + 20

Find x.

A) 70°
B) 80°
C) 90°

Question 4

Interior angle = x
Exterior angle = 2x − 10

Find x.

A) 60°
B) 70°
C) 80°

Question 5

Why are the two exterior angles equal?

A) Because they are interior angles
B) Because they form linear pairs with the same angle
C) Because they are adjacent angles

Answers

1️⃣ B – 110°

2️⃣ C – 120°

3️⃣ B – 80°

4️⃣ B – 70°

5️⃣ B – Because they form linear pairs with the same angle

Practice

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Continue Learning

1. Types of Triangles
2. Triangles (Basics)
3. Sum of Angles of a Triangle is 180° (Proof)
4. Find the Missing Angle of a Triangle
5. Sum of Exterior Angles of a Triangle (Proof)
6. Exterior Angle Theorem of a Triangle
7. Two Exterior Angles at a Vertex are Equal (Proof)
8. Two Exterior Angles are Equal at a Vertex (Quick Proof)

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