maths/MUSTKNOW/cosineRule


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trig rule, used to find missing sides on a triangle

a^2 = b^2 + c^2 - 2bc cos(A)

when rearranged can be:

cos(A) = (b^2 + c^2 - a^2) / (2bc)  // use this one when you only have side lengths

when using this use cos^-1 

example in folder p1