How do you find the measure of each of the angles of a triangle given the measurements of the sides are 11, 11, 15?
Using the Law of Cosines. See explanation for details.
First we can use the Law of Cosines to find the angle opposite to the triangle's base (i.e. the longest side):
To calculate the remaining angles we can use the fact that the triangle is isosceles.
Using this fact we can write that: