Question

if three sides of a triangle are 18.5,13.5,7 then find the angles between them?

Answer 1

a = 18.5    b = 13.5    c = 7

cos A = (b² + c² - a² )/ 2 bc     = 125.965 deg
cos B = (a² + c² - b²) / 2 ac      =  36.2 deg
COS C = (a² + b² - c²) / 2 ab   or  180 - A - B  = 17.834 deg