Understanding Angles, Lines, and Polygons

Front

Angle

Back

Space between two lines that meet at a point

Front

Right angle

Back

90°

Front

Acute angle

Back

Less than 90°

Front

Obtuse angle

Back

More than 90° but less than 180°

Front

Straight angle

Back

180°

Front

Parallel lines

Back

Lines that never meet

Front

Perpendicular lines

Back

Lines that meet at a right angle

Front

Intersecting lines

Back

Lines that cross each other

Front

Polygon

Back

A closed shape with straight sides

Front

Triangle

Back

3 sides