Head First 2D Geometry

276 Chapter 7

equal sides and angles

Perimeter

Volume

Internal angles

Carpenters want these angles.

If you put area here

that’s cool, too! You’ll

see why in a bit.

Side lengths

What properties of the hot tubs do you need to work out to satisfy:

1. The bands?

2. The environment engineer?

3. The carpenters?

How does it help you that the tubs are all regular polygons?

Since all the sides on a regular polygon are the same length, then all the angles are equal

too, so we’ve only got to find one side and one angle—all the others will match.

Regular polygons have equal sides and angles

Six-sided polygon:

REGULAR six-

sided polygon:

All these angles

can be different.

All these angles

are equal.

Sides are

various lengths.

Sides all equal

length, too.

This isn’t just

true for regular

six-sided polygons.

This is true for

regular polygons

with any number

of sides.

Any six-sided polygon could have six different side lengths and

six different angles. But fortunately for us, all the hot tubs are

regular polygons. A six-sided regular polygon has six sides of

equal length and six equal angles.

People sit around the edges.