Hello Tbeck227, how to find the angle measure of an isosceles triangle if you only know the side lengths is, for all the angles, though it would be
unreasonable to use it for all three, since once we know two the third
is easy. Lubin suggested using the Cosine Law for the first calculation
and the Sine Law for the second. This is faster than Cosine Law done
twice. The suggestion is to use the Cosine Law to determine the angle
opposite a largest side.
