http://www.ck12.org Chapter 10. Perimeter and Area
sin 36◦=460. 5
r
→r=460. 5
sin 36◦
≈ 783. 45 f t.Therefore, the total distance across is 590. 66 + 783. 45 = 1374. 11 f t.
Vocabulary
Perimeteris the distance around a shape. The perimeter of any figure must have a unit of measurement attached to
it. If no specific units are given (feet, inches, centimeters, etc), write “units.”Areais the amount of space inside a
figure. Area is measured in square units. Thecenterandradiusof a regular polygon is the center and radius of the
circumscribed circle. Anapothemis a line segment drawn from the center of a regular polygon to the midpoint of
one of its sides.
Guided Practice
- Find the area of the regular octagon in Example C.
- Find the area of the regular polygon with radius 4.
- The area of a regular hexagon is 54
√
3 and the perimeter is 36. Find the length of the sides and the apothem.Answers: