Question

Given: ∠1 and ∠2 are complementary angles.
Prove: ∠3 and ∠4 are complementary angles.

Answer 1

Two angles are called complementary when their measures add to 90 degrees. ∠1 is 60 degrees ∠2 is 30 degrees so if you add it up, the answer is 90 degrees.

∠4 + ∠3 = answer has to be 90 degrees to call it a complementary angle

30 degrees + 60 degrees = 90 degrees

Answer 2

If I had to pick between these, it would be definition of complementary angles.

Hope this helps!