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.

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.