Test your understanding of exterior angles at a vertex.
Try to answer the questions before checking the answers at the bottom of the page.
Question 1
If one exterior angle is \(80^\circ\), what is the other exterior angle?
A) \(40^\circ\)
B) \(80^\circ\)
C) \(160^\circ\)
Question 2
If one exterior angle is \(120^\circ\), what is the other exterior angle?
A) \(60^\circ\)
B) \(90^\circ\)
C) \(120^\circ\)
Question 3
One exterior angle is \(x\)
The other is \(x + 20\)
Find \(x\).
A) \(10^\circ\)
B) \(20^\circ\)
C) \(30^\circ\)
Question 4
One exterior angle is \(2x\)
The other is \(x + 30\)
Find \(x\).
A) \(20^\circ\)
B) \(30^\circ\)
C) \(40^\circ\)
Question 5
Why are the two exterior angles equal?
A) Because they are adjacent angles
B) Because they are vertical angles
C) Because they are interior angles
Question 6
If one exterior angle is \(105^\circ\), what is the other exterior angle at the same vertex?
A) \(75^\circ\)
B) \(90^\circ\)
C) \(105^\circ\)
Question 7
One exterior angle is \(x\).
The other exterior angle is \(3x-40^\circ\).
Find \(x\).
A) \(20^\circ\)
B) \(30^\circ\)
C) \(40^\circ\)
Question 8
One exterior angle is \(4x+10^\circ\).
The other exterior angle is \(6x-30^\circ\).
Find \(x\).
A) \(10^\circ\)
B) \(20^\circ\)
C) \(30^\circ\)
Question 9
How are the two exterior angles at the same vertex formed?
A) By extending only one side of the triangle
B) By drawing a line through the centre of the triangle
C) By extending both sides that meet at the vertex
Question 10
One exterior angle is \(135^\circ\).
What is the measure of the other exterior angle?
A) \(135^\circ\)
B) \(45^\circ\)
C) \(225^\circ\)
Answers
- B – \(80^\circ\)
- C – \(120^\circ\)
- B – \(20^\circ\)
- B – \(30^\circ\)
- B – Because they are vertical angles
- C – \(105^\circ\)
- A – \(20^\circ\)
- B – \(20^\circ\)
- C – By extending both sides that meet at the vertex
- A – \(135^\circ\)
Practice
- Take the Quiz (Current page)
Continue Learning
- Sum of Exterior Angles of a Triangle (Proof)
- Exterior Angle Theorem of a Triangle
- Two Exterior Angles at a Vertex are Equal (Proof)
- Two Exterior Angles are Equal at a Vertex (Quick Proof)