Luna is building a two piece roof for her shed. The width of the shed is 8ft, one roof piece is 4ft long and the other is 6ft long. What angle is formed at the peak of the roof?

Question

Ans: 104 degrees ( I need the work)

Answer 1

divide all by two to make it easier
2,3,4

law of cosines
c^2 = a^2 + b^2 - 2 a b cos C
16 = 4 + 9 -2*2*3cos C

12 cos C = -3
cos C = -.25
C = 104.5 degees