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pythontrigonometrytriangle

Finding third side of triangle using law of cosine. python


For some reason the answer I get in the program is 7.091341682475861 It is supposed to be 6.66634. Can someone please explain to me what I am doing wrong. The equation is fairly simple and straightforward?

import math as mt
 def third_side(a, b, c):
                return mt.sqrt((a * a) +
                       (b * b) - 2 * a * b * mt.cos(c))
            c = 37
            a, b = 8, 11
            print(third_side(a,b,c))

Solution

  • According to https://docs.python.org/3/library/math.html#math.cos

    math.cos takes input in radians. You should do mt.cos(c/180*mt.pi)

    import math as mt
    def third_side(a, b, c):
        return mt.sqrt((a * a) + (b * b) - 2 * a * b * mt.cos(c/180*mt.pi))
    c = 37
    a, b = 8, 11
    print(third_side(a,b,c))