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.
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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.
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