At night, a security camera pans over a parking lot. The camera is on a post at point a which is 53m from point c and 71 m from point b.the distance from B to c is 68m. Calculate the angle through which the camera pans

Answer 1

the law of cosines says

68^2 = 53^2 + 71^2 - 2*53*72 cosθ
so,
cosθ = (68^2-53^2-71^2)/(-2*53*72) = 0.42269
θ = 65°