Pre-Calculus - Using the Double Angle Formula to Evaluate for Cosine of an Angle and Triangle

The video tutorial covers solving trigonometric problems by creating triangles for angles not on the unit circle. It explains the use of Pythagorean triples to simplify calculations and demonstrates evaluating cosine using various methods. The tutorial emphasizes understanding constraints and applying formulas effectively.

What is a Pythagorean triple and how does it relate to the problem discussed?

Describe the process of evaluating the cosine of angle U as outlined in the text.