Evaluate the double angle of sine from a triangle

The video tutorial explains how to determine the quadrant for a given angle theta, specifically between π and 3π/2, and how to correctly draw the triangle in the third quadrant. It discusses the concept of Pythagorean triples, using a 3-4-5 triangle as an example, and explains how to calculate the sine of a double angle using the formula 2sin(u)cos(u). The tutorial emphasizes understanding the signs of trigonometric functions in different quadrants and provides a step-by-step calculation of the sine of double theta.

What values are used to find the sine and cosine of Theta in the calculations?

What is the final result of the multiplication of sine and cosine as described in the text?