Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 1 - Review Exercises - Page 99: 77

Answer

The measure of each angles is $ 25^{\circ} , 35^{\circ} $ and $ 120^{\circ} $.

Work Step by Step

let the angles of a triangle are $ A,B $ and $C$. Sum of all angles of a triangle is $ =180^{\circ} $. $ A+B+C =180^{\circ} $ ... (1) one angle of a triangle measures $ 10 ^{\circ} $ more than the second angle. In the equation form. $ A=B+10^{\circ} $ ... (2) The measure of the third angle is twice the sum of the measures of the first two angles. in the equation form. $ C=2(A+B) $ ... (3) Substitute the value of $ A $ from equation (2) to equation (3). $ C=2(B+10^{\circ}+B) $ $ C=2(2B+10^{\circ}) $ $ C=4B+20^{\circ} $ ... (4) Substitute the values of $ A $ and $ C $ from equation (2) and (4) into equation (1). $ B+10^{\circ}+B+4B+20^{\circ} =180^{\circ} $ Simplify. $ 6B+30^{\circ} =180^{\circ} $ $ 6B =180^{\circ}-30^{\circ} $ $ 6B =150^{\circ} $ $ B =\frac{150^{\circ}}{6} $ $ B =25^{\circ} $. Substitute the value of $ B $ into equation (2). $ A=25^{\circ}+10^{\circ} $ $ A=35^{\circ} $. Now Substitute the value of $ B $ into equation (4). $ C=4(25^{\circ})+20^{\circ} $ $ C=100^{\circ}+20^{\circ} $ $ C=120^{\circ} $.
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