# --------------------------------- # File: Xiang/cosLaw.py # Author: Mihaela Malita # Law of cos: c**2 = a**2 + b**2 - 2ab cos(C) # Xiang Appendix I p. 275 # Find the C angle # x = -0.3125 # C in radians is arccos(x) = 1.88862003072 # C in grades = 108.209956864 # --------------------------------- import math # given angle in radians transform in grades # r: 0 - 2pi and g: 0 - 360 def radian_grades (r): g = 180 * r / math.pi return g def main(): # triangle a,,b,c a = 4.0 b = 2.0 c = 5.0 x = ( a**2 + b**2 - c**2) / (2 * a * b) print "x = ",x C = math.acos(x) # angle C in radians print "C in radians is arccos(x) = ", C print "C in grades = ", radian_grades(C) main()