Adjacent complementary angles (or adjacent angles on a straight line [1]), two angles have a common edge, and their other side is an opposite extension line. Two angles with this relationship are called adjacent complementary angles. (that is, the definition of adjacent complementary angles)
If the sum of the two angles is 90, then we say that the two angles are complementary, or that one angle is complementary to the other. For example:
∠A = 30, ∠B = 60, ∠A+∠B = 90, then ∠ A and ∠ B are complementary angles ".
∠A = 15, ∠B = 75, ∠A+∠B = 90. It is said that ∠ A and ∠ B are complementary angles.