1. Relating Terms ‘Perpendicular’ and ‘Complementary Angles’

2. Suppose rays AB and AD are perpendicular Therefore, the measure of angle BAD is 90 0 So if the angle BAD is cut into ‘parts’, then the sum of these parts must still be 90 0. A B D

3. If angle BAD is cut into ‘parts’, then the sum of these parts must still be 90 0. Recall, the measure of angle BAD is 90 0 Since the measures of angles BAP and PAD add to be 90 0, the angles are called complementary A B D P

4. In Summary… We were given a pair of perpendicular rays, therefore the angle they formed measured 90 0. We cut this angle into two parts, so the sum of measures of these parts (angles) must still be 90 0. Since these angles have a sum of 90 0, they are called complementary.

5. Thanks for watching!