How do you solve a mathematical question if you are given all the sides of a triangle and you are asked to look for one angle?

Answer 1

Use the Law of Cosines, If the sides are denoted by a, b, c, and the angle opposite side a is called A, then

a² = b² + c² - 2bccosA

Similarly, b² = a² + c² - 2accosB and c² = a² + b² - 2abcosC.