Which statment below is ALWAYS TRUE?

Question

A. Complementary angles are both acute angles.

B. Any two acute angles are complementary angles.

C. Supplementary and Complementary angles are always adjacent angles. 

D. Supplementary angles are both obtuse angles.

Answer 1

Complementary angles are two angles whose sum is 90^o. Supplementary angles are two angles whose sum is 180^o. Because of this, two complementary angles must necessarily be acute, as both of them must be less than 90^o. Two supplementary angles must be either two right angles, or one of them is acute while the other is obtuse. Because of this, the correct answer is A.