Use of the ancient law of cosines to determine the angle between two sides of
a triangle, given lengths of all three sides.
This is a generalization of Pythagoras' Theorem.
Usage
LawofCosines(sides)
Value
a numeric constant giving the angle in between the sides corresponding to the
first two components in sides. Result is expressed in degrees.
Arguments
sides
a numeric vector of length 3, containing the side lengths.