Question

Find the measure of the exterior angle. (hint: find x first, then plug it into the exterior angle)

Answer 1

exterior angle = 65°

Explanation:

the exterior angle of a triangle is equal to the sum of the 2 opposite interior angles

3x - 10 is an exterior angle of the triangle

with 25 and x + 15 the 2 opposite interior angles , then

3x - 10 = x + 15 + 25

3x - 10 = x + 40 ( subtract x from both sides )

3x - x - 10 = x - x + 40 ( simplify both sides )

2x - 10 = 40 ( add 10 to both sides )

2x - 10 + 10 = 40 + 10 ( simplify both sides )

2x = 50 ( divide both sides by 2 )

`(2)/(2)` x =
`(50)/(2)` , that is

x = 25

Then

exterior angle = 3x - 10 = 3(25) - 10 = 75 - 10 = 65°