Question

Angle A and angle B are complementary. If m angle A = (9x – 40)º, m angle B = (2x + 42)°, then find m angle B.​

Answer 1

Explanation:

Solution,

Given,

angle A = (9x-40)°

angle B= (2x+42)°

angle A and angle B are complementary

We know that,

complementary means having 90° when added,

Therefore,

(9x-40°)+(2x+42)°=90°

9x°-40°+2x°+42°=90°

11x°+2°=90°

11x°=90°-2°

11x°=88°

x°=88°/11

x°=8

Hence,

angle A=(9x-40)°

=(9×8-40)°

=32°

angle B=(2x+42°)

=(2×8+42)°

=58°

Answer 2

angle B = 58

Explanation:

Complementary means that both angles add up to 90°.

Both angles are 9x-40 and 2x+42. Sum of both equal 90°

9x-40+2x+42=90

Combine like terms — we get:

11x+2=90

11x=90-2

11x=88

x = 8

Since we want to find angle B, substitute x = 8 in 2x+42

angle B = 2(8)+42

= 16+42

= 58

Therefore, angle B is 58.