Supplementary Angles (Mathematics Lesson)
Supplementary AnglesSupplementary angles are two angles which add up to a straight angle.
Two angles that add to 180° are are said to supplement each other.
A Real Example of Supplementary AnglesAngles of 100° and 80° are supplementary angles.
100° + 80° = 180°.
How to Find a Supplementary AngleQuestion: What angle supplements the 56° angle below?
Step 1: The 56° angle and θ are supplementary angles. They add up to 180°.
56° + θ = 180°.
Step 2: Subtract the 56° angle from 180°.
θ = 180° - 56° = 124°.
The supplementary angle is 124°.
Another Real Example of Supplementary AnglesThe slider below shows a real example of supplementary angles in mathematics; the interior and exterior angles of a polygon:
Top TipWHAT TYPES OF ANGLES ARE SUPPLEMENTARY?
Supplementary angles form a Straight Line.
NoteWHAT'S IN A NAME?
Supplementary comes from the Latin word 'supplementum' meaning "filled up".
This is because an angle is filled up to form a straight line.
SUPPLEMENTARY ANGLES CAN BE ACUTE, RIGHT AND OBTUSE
Supplementary angles can either be: