A triangle has sides A, B, and C. Sides A and B are of lengths 4 and 3, respectively, and the angle between A and B is (5pi)/6 . What is the length of side C?
1 Answer
Feb 10, 2016
≈ 2.05
Explanation:
In this triangle 2 sides and the angle between them are known , hence use the ' cosine rule '.
for this triangle the cosine rule is :
C^2 = A^2 + B^2 - ( 2ABcos((5pi)/6)) hence
C^2 = 4^2 + 3^2 - ( 2 xx 4 xx 3 xxcos((5pi)/6))
C^2 = 16 + 9 - (24cos((5pi)/6)) = 25 - 20.78 = 4.22
now
C^2 = 4.22 rArr C = sqrt4.22 ≈ 2.05
