Question

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

What is the measure of ∠B?

Enter your answer in the box.
point theif = ban

Answer 1

• <B be x

Complementary angles have sum 90°

`\\ \sf\longmapsto x+21=90`

`\\ \sf\longmapsto x=90-21`

`\\ \sf\longmapsto x=69`

Answer 2

• 69°

Explanation:

Complementary angles sum to 90°.

We have the measure of one angle, find the missing one as below.

• m∠A + m∠B = 90°
• 21° + m∠B = 90°
• m∠B = 90° - 21°
• m∠B = 69°