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9² = 12² + 15² - 2 (12) (15) cos (B)
81 = 144 + 225 - 360 cos(B)
81 = 369 - 360 cos (B)
360 cos (B) = 369 - 81
360 cos (B) = 288
cos (B) = 0.8
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Answer: Cosine B = 0.8
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12² = 15² + 9² - 2 (15)(9) cos (A)
144 = 225 + 81 - 270 Cos A
144 = 306 - 270 Cos A
270 Cos A = 162
Cos A = 3/5 or 0.6
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Answer: Cosine Angle A = 3/5
Answer:

Step-by-step explanation:
There's no need of hypotenuse for finding area of the triangle. To find the area of a triangle ,
Formula is =
Base of the triangle = 10 cm
Height of the traingle = 3 cm
Area of the triangle = 
For this problem, you're going to need to use trig. More specifically, you need to use the tangent function:
tan (value) = opposite/adjacent
tan 75 = opposite/8 (Here, the opposite side is the length of the ladder)
8 * tan 75 = opposite
29.8564065 = opposite
So, the ladder is 29.9 feet.