In △ABC, a=34, b=18, and c=17. Find m∠A.

A. 14.1

B. 132.6

C. 152.5

D. 101.5

C. m < A = 152.5 degrees.

Step-by-step explanation:

Use the Cosine Rule:

a^2 = b^2 + c^2 - 2. b. c. cos A

34^2 = 18^2 + 17^2 - 2.18.17 cos A

2.18.17 cos A = 18^2 + 17^2 - 34^2

cos A = (18^2 + 17^2 - 34^2) / (2.18.17)

cos A = - 0.88725

m < A = 152.5 degrees.