Question

Angles that are congruent and supplementary must be
a. acute angles.
b. obtuse angles.
c. straight angles.
d. right angles.

Answer 1

Answer: d. right angles.

Step-by-step explanation:

• If the sum of two angles is $180^{\circ}$, then they are called as supplementary angles.

• If two angles are equal then they are said to be congruent.

Let a and b be two angles which are congruent and supplementary

Then a=b [congruent]

And $a+b=180^{\circ}$

$2a=180^{\circ}\\\Rightarrow a=90^{\circ}$

Hence, the angles  that are congruent and supplementary must be right angles.