The lengths of the sides of the triangle are 10,10,12. Find the cosine of the angle between the sides

The lengths of the sides of the triangle are 10,10,12. Find the cosine of the angle between the sides of the triangle, unequal in length.

According to the cosine theorem, the square of the side of a triangle can be defined as the sum of the squares of the other two sides minus their doubled product by the cosine of the angle between them. For a given triangle, you can write:

10 ^ 2 = 10 ^ 2 + 12 ^ 2 – 2 * 10 * 12 * cos α, where α is the angle between sides equal to 10 and 12.

240 * cos α = 100 + 144 – 100;

240 * cos α = 144;

cos α = 144/240 = 0.6.