Question

1. ∠5 is a supplement of ∠6, and m∠5 = 78°. find ∠6.

Explanation:

Step1: Recall supplementary angle definition

Supplementary angles sum to $180^\circ$, so $m\angle5 + m\angle6 = 180^\circ$.

Step2: Substitute known angle measure

Substitute $m\angle5=78^\circ$: $78^\circ + m\angle6 = 180^\circ$.

Step3: Solve for $m\angle6$

Rearrange to isolate $m\angle6$: $m\angle6 = 180^\circ - 78^\circ$.

Answer:

$102^\circ$