Trigonometry
posted by Anonymous on .
Given triangle ABC with a = 16, b = 14, and Beta = 54°, find the value of c.
A. 3.1 and 20
B. 4.1 and 15
C. 15
D. 3.1

Use Law of Cosines:
cosB = (a^2+c^2b^2)/2ac.
0.58779 = (256+c^2196)/32c
0.58779 = (c^2+60)/32c
Cross multiply:
18.81c = c^2+60
c^218.81c+60 = 0.
c = 4.1,and 14.7. Use Quadratic Formula.