How_To_Be_Good_At_Math

GEOMETRY • REGULAR AND IRREGULAR POLYGONS 213

Regular and irregular

polygons

A polygon is a 2D shape made of straight sides. Regular polygons have sides

that are all the same length and angles of equal size. Irregular polygons have

sides of different lengths and different-sized angles.

TRY IT OUT

Odd one out

Only one of these five-sided

polygons is a regular polygon, with

sides of the same length and equal-

sized angles. Can you spot it?

Regular triangle Irregular triangle

Irregular quadrilateral

Irregular hexagon

Regular quadrilateral

Answer on page 320

All six sides are the

same length, and the

angles are equal

All three sides are different

lengths, and the angles are

different sizes

The sides can be

different lengths

Regular hexagon

Triangle

A regular triangle has a special

name – an equilateral triangle.

Different irregular triangles also

have special names. Find out

more on page 215.

Quadrilateral

Quadrilaterals are four-

sided shapes. A regular

quadrilateral is called a square.

Hexagon

A six-sided polygon

is called a hexagon.

212_213_2D_shape_Regular_irregular_polygons.indd 213 29/02/2016 18:04