A triangle has sides A, B, and C. Sides A and B are of lengths 33 and 22, respectively, and the angle between A and B is (5pi)/12 5π12. What is the length of side C?

1 Answer
Feb 13, 2016

C ≈ 3.15

Explanation:

In this triangle , 2 sides and the angle between them are known.In this situation to solve for C use color(blue)(" cosine rule ") cosine rule

for this triangle the cosine rule is

C^2 = A^2 + B^2 - (2ABcostheta)C2=A2+B2(2ABcosθ)

here A = 3 , B = 2 and theta = (5pi)/12 θ=5π12
substitute these values into formula

C^2 = 3^2 + 2^2 - ( 2 xx 3 xx2cos((5pi)/12 )C2=32+22(2×3×2cos(5π12)

= 9+4 - 3.1 = 13 - 3.1 = 9.9

C^2 = 9.9 rArr C = sqrt9.9 ≈ 3.15C2=9.9C=9.93.15