Basic College Mathematics (10th Edition)

Published by Pearson
ISBN 10: 0134467795
ISBN 13: 978-0-13446-779-5

Chapter 8 - Geometry - 8.5 Triangles - 8.5 Exercises - Page 565: 18


The unknown angle is 145$^{\circ}$.

Work Step by Step

The sum of the angle in a Triangle is 180∘. Here we will solve for the unknown angle. We will label it X. Therefore: 180$^{\circ}$ = 20$^{\circ}$ + 15$^{\circ}$ + X X = 180$^{\circ}$ - (20$^{\circ}$ + 15$^{\circ}$) X = 180$^{\circ}$ - (35$^{\circ}$) X = 145$^{\circ}$
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