Pre-Calculus - Evaluating for the Double Angle of Sine with a Triangle

The video tutorial explains how to calculate the sine of 2U given that sine of U is -4/5. It introduces the formula for sine of 2U, which is 2 times sine of U times cosine of U. The tutorial then guides the viewer through determining the cosine of U by constructing a triangle in the correct quadrant, using the Pythagorean triple to find the missing side. Finally, it demonstrates how to plug the values into the formula to find the sine of 2U.

What is the formula for the sine of two U?

How do you determine the cosine of U when it is not on the unit circle?

Explain how to find the sine and cosine values given the constraints of the angle.

What is the significance of the Pythagorean triple in this context?

What are the values of sine of U and cosine of U derived in the text?