Question

∠A and ∠B are complementary. The measure of ∠A is 21°.

What is the measure of ∠B?

Enter your answer in the box.

°

Answer 1

∠B = 69°

Explanation:

Complementary angles are such pairs of angles that sum up to 90°. In this case, we are given that ∠A and ∠B are a pair of complementary angles. This means that ∠A and ∠B sum up to 90°.

⇒
`\angle A + \angle B = 90\°`

⇒
`21\° + \angle B = 90\°` [∠A = 21°]

⇒
`\angle B = 90 - 21`

⇒
`\angle B = 69\°`

Answer 2

complementary angles is when the sum of two angles is equal to 90 degrees.

∠A + ∠B = 90°

21° + ∠B = 90°

∠B = 90° - 21°

∠B = 69°