You can determine the complement of a given angle by subtracting it from 90°. For example, the complement of 28° is 62° since 90° - 28° = 62°.

Let us find the complementary angle for an angle, say x. To find its complementary angle, subtract x from 90. So, the complementary angle for x is (90 – x) degrees.

How to Find Complementary Angles? Suppose if one angle is x then the other angle will be 90 ° – x. Hence, we use these complementary angles for trigonometry ratios, where one ratio is complementary to another ratio by 90 degrees such as; sin (90° – A) = cos A and cos (90° – A) = sin A tan (90° – A) = cot A and cot (90° – A) = tan A

An easy way to create complementary angles is with a right triangle. Simply draw a straight line beginning at the right angle vertex and through the triangle. No matter where you draw the line, you have created two complementary angles.

Try this: Complementary angles add up to 90° - example: 15° & 75° are complementary (added together, they form a right angle) -and- Supplementary angles add up to 180° - example: 50° & 130° are supplementary (added together, they form a straight line)