Trigonometry (10th Edition)

Published by Pearson
ISBN 10: 0321671775
ISBN 13: 978-0-32167-177-6

Chapter 7 - Review Exercises - Page 346: 55

Answer

Both sides of the equation for the Law of Tangents are equal, which verifies this law for the information given in the question.

Work Step by Step

$a = 2$ $b = 2\sqrt{3}$ $A = 30^{\circ}$ $B = 60^{\circ}$ We can find the value of the left side of the equation for the Law of Tangents: $\frac{tan~\frac{1}{2}(A-B)}{tan~\frac{1}{2}(A+B)} = \frac{tan~\frac{1}{2}(30^{\circ}-60^{\circ})}{tan~\frac{1}{2}(30^{\circ}+60^{\circ})}$ $\frac{tan~\frac{1}{2}(A-B)}{tan~\frac{1}{2}(A+B)} = \frac{tan~\frac{1}{2}(-30^{\circ})}{tan~\frac{1}{2}(90^{\circ})}$ $\frac{tan~\frac{1}{2}(A-B)}{tan~\frac{1}{2}(A+B)} = \frac{tan~(-15^{\circ})}{tan~(45^{\circ})}$ $\frac{tan~\frac{1}{2}(A-B)}{tan~\frac{1}{2}(A+B)} = -0.2679$ We can find the value of the right side of the equation for the Law of Tangents: $\frac{a-b}{a+b} = \frac{2-2\sqrt{3}}{2+2\sqrt{3}} = -0.2679$ Both sides of the equation for the Law of Tangents are equal, which verifies this law for the information given in the question.
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