Elementary Geometry for College Students (7th Edition)

Published by Cengage
ISBN 10: 978-1-337-61408-5
ISBN 13: 978-1-33761-408-5

Chapter 7 - Section 7.3 - More about Regular Polygons - Exercises - Page 343: 21

Answer

(a) $140^{\circ}$ (b) $135^{\circ}$

Work Step by Step

(a) We can find the number of vertices of the polygon: $40^{\circ} = \frac{360^{\circ}}{n}$ $n = \frac{360^{\circ}}{40^{\circ}}$ $n = 9$ We can find the interior angle of this polygon: $\frac{(n-2)(180^{\circ})}{n} = \frac{(9-2)(180^{\circ})}{9} = 140^{\circ}$ (b) We can find the number of vertices of the polygon: $45^{\circ} = \frac{360^{\circ}}{n}$ $n = \frac{360^{\circ}}{45^{\circ}}$ $n = 8$ We can find the interior angle of this polygon: $\frac{(n-2)(180^{\circ})}{n} = \frac{(8-2)(180^{\circ})}{8} = 135^{\circ}$
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