Understanding Angles and Lines

Front

Acute Angle

Back

Less than 90°

Front

Right Angle

Back

Exactly 90°

Front

Obtuse Angle

Back

Greater than 90° and less than 180°

Front

Straight Angle

Back

Exactly 180°

Front

Reflex Angle

Back

Greater than 180° and less than 360°

Front

Line Segment

Back

Part of a line with two endpoints

Front

Line

Back

Extends infinitely in both directions

Front

Parallel Lines

Back

Lines that never meet

Front

Perpendicular Lines

Back

Lines that intersect at 90°

Front

Complementary Angles

Back

Two angles that add up to 90°