Question

In parallelogram ABCD, m∠ADC = 60°.

What is m∠DCB?



___°

Answer 1

Answer: 120°

Explanation:

Since it is a parallelogram, then opposite sides are parallel. Since ∠ADC is next to ∠DCB, they are supplementary angle (which means the sum of their angles is 180°).

∠ADC + ∠DCB = 180°

60 + ∠DCB = 180°

∠DCB = 120°