Evaluate for sine cosine and tangent using reference angles

The video tutorial explains how to evaluate the sine, cosine, and tangent of -840 degrees using coterminal and reference angles. It covers the concept of negative angles, finding reference angles both graphically and algebraically, and calculating trigonometric values. The tutorial emphasizes the importance of understanding the unit circle and the properties of angles in different quadrants.

How do the signs of the sine and cosine values change in the third quadrant?

What is the sine of -840 degrees and why is it negative?

Describe how to calculate the tangent of -840 degrees using the coordinates.