Question

I have no idea how to do this!

Answer 1

D) 55

Explanation:

Since all interior angles of triangles equal 180 degrees, we can easily add 105 and 20 together to get 125 and subtract that from 180 to get 55 degrees, which is measurement of the missing angle of the triangle shown. Since the triangles create vertical angles, we know that the missing angle is 55 degrees, as vertical angles are congruent.

Answer 2

D = 55

Explanation:

The ? is a vertical angle to the angle in the triangle. Vertical angles are equal. So if we find the angle in the triangle, we find ?

The angles of a triangle add to 180. We will call the unknown angle x

105+20 + x = 180

Combine like terms

125+x = 180

Subtract 125 from each side

125-125+x = 180-125

x = 55

Since ? and x are vertical angles

? = 55