Answer: d. right angles.
Step-by-step explanation:
- If the sum of two angles is [tex]180^{\circ}[/tex], 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 [tex]a+b=180^{\circ}[/tex]
[tex]2a=180^{\circ}\\\Rightarrow a=90^{\circ}[/tex]
Hence, the angles that are congruent and supplementary must be right angles.
