- Naming of Angles (acute, right, complementary, obtuse, straight, supplementary reflex angles and angle at a point)
- Units and Measurement of Angles
- Angles between Lines (vertically opposite, angle on a straight line and angle at a point)
- Angles between Parallel Lines (adjacent, alternate and corresponding angles)
Names of Angles
As the angle increases, the name changes:
Two angles are supplementary when they add up to \(180\) degrees. They don’t have to be next to each other, just so long as the total is \(180\) degrees.
\(60^o\) and \(120^o\) are supplementary angles.
\(93^o\) and \(87^o\) are supplementary angles.
Two angles are complementary when they add up to \(90\) degrees (a right angle).
They don’t have to be next to each other, just so long as the total is \(90\) degrees.
\(60^o\) and \(30^o\) are complementary angles.
\(5^o\) and \(85^o\) are complementary angles.
- Find the angle that is complementary to (a) \(75^o\) (b) \(105^o\).
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