Use the Law of Cosines to solve the triangle.

Question

a = 1.35, b = 0.78, c = 1.18

Calculate cosA

Answer 1

The sides of triangles are a = 1.335 , b  = 0.78 , c  = 1.18

Use the law of Cosines

CosA  = (b² + c² - a²)/2bc

CosA  = [(0.78)² + (1.18)² - (1.35)²]/2(0.78)(1.18)

CosA  = [0.6084 + 1.3924 - 1.8225]/1.8408

CosA  = 0.1783/1.8408

CosA  = 0.096.