Question

If mZ1= 140, what is m_3?
900
500
1300
400

Answer 1

∠ 3 = 50°

Explanation:

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

∠ 1 is an exterior angle of the triangle, so

90° + ∠ 3 = ∠ 1

90° + ∠ 3 = 140° ( subtract 90° from both sides )

∠ 3 = 50°