Trigonometry (10th Edition)

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

Chapter 7 - Applications of Trigonometry and Vectors - Section 7.1 Oblique Triangles and the Law of Sines - 7.1 Exercises - Page 298: 45

Answer

$356$ cm$^{2}$

Work Step by Step

The area of the triangle is half the product of the length of two sides and the sine of the angle included between them: $Area=\frac{1}{2}ac \sin B$ We substitute the values of $a,B$ and $c$ in this formula and solve: $Area=\frac{1}{2}ac \sin B$ $Area=\frac{1}{2}(30.4)(28.4) \sin 124.5^{\circ}$ $Area=\frac{1}{2}(863.36) \sin 124.5^{\circ}$ $Area=431.68 \sin 124.5^{\circ}$ Using a calculator, $\sin 124.5^{\circ}=0.8241$. Therefore, $Area=431.68 \sin 124.5^{\circ}$ $Area=431.68(0.8241)$ $Area=355.75\approx356$ Therefore, the area of the triangle is $356$ cm$^{2}$.
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