Use the Law of Cosines. Find b to the nearest tenth.

Use the Law of Cosines. Find b to the nearest tenth.
$Triangle ABC with the measure of angle B = 48, the side opposite angle C = 85, and the side opposite angle “A” = 60.$

	A.	102.2
	B.	62.4
	C.	132.9
	D.	63.2

Find the area of the triangle. Give the answer to the nearest tenth. The drawing may not be to scale.
$A triangle with one angle equal to 70 degrees. The sides of that angle are 9 cm and 15 cm.$

	A.	126.9 cm²
	B.	63.4 cm²
	C.	23.1 cm²
	D.	185.5 cm²

$In triangle JKL, j = 9 inches, k = 5 inches and the measure of angle L = 43. Find the measure of angle J.$

	A.	28º
	B.	59º
	C.	32º
	D.	105º

asked Oct 7, 2014 in TRIGONOMETRY by tonymate Pupil

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1 Answer

Find the value of b by using the cosine rule:

b² = a² + c² - 2ac cosB

From the figure:

a = 60, c = 85, and B = 48°

b² = 60² + 85² - 2*60*85 cos(48°)

= 3999.87

b = 63.244 ≈ 63.2

So option D is correct

answered Oct 8, 2014 by bradely Mentor
edited Oct 8, 2014 by bradely

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