Question

find angle whose complement is equal to angle

Answer 1

A+C = 90
A=C
A+A = 90
2A = 90
A = C= 45

Answer 2

Define x:

Let the angle be x

Complementary angles are angles that add up to 90º

Find the other angle in term of x:

Its complementary angle is equal to angle itself

therefore the other angle is also x

Solve x:

x + x = 90

2x = 90

x = 90 ÷ 2

x = 45º

Answer: The angle is 45º. Its complementary angle is also 45º