Exterior angle of a triangle
An exterior angle and its interior angle make a straight line. It also equals the sum of the two far interior angles.
Loading a question…
You've done today's 10 free questions.
Come back tomorrow for 10 more, or get unlimited practice with a membership.
Want more today? Print 20 more questions free, with the answers.
Already a member? Sign in.
See worked examples
Two angles inside a triangle are 98° and 59°. What is the exterior angle at the third vertex, in degrees?
Answer: 157
Two angles inside a triangle are 25° and 106°. What is the exterior angle at the third vertex, in degrees?
Answer: 131
Two angles inside a triangle are 78° and 60°. What is the exterior angle at the third vertex, in degrees?
Answer: 138
Tip: An exterior angle and its interior angle make a straight line. It also equals the sum of the two far interior angles.
Print a worksheet of this skill New questions and an answer key, free.
Up next
- Next in this topic Write and solve equations: complementary angles Year 7
- Ready for more Corresponding angles and parallel lines Year 8
Print a free worksheet with answers (20 questions).
Practise without limits
Members practise as much as they like, every day, and get the printable packs and lessons too.