Proof of the Trig Sum and Difference Formulas

Proof of the sum and difference formulas for sine, cosine and tangent

Trig Substitution & Identities

Using the trig identities for substituting a Pythagorean looking expression.

Using Sum & Difference Formulas

Here we find the trig functions of other angles based on the sum and difference of two angles, the double or half angle. We will prove these formulas in a different video

Radians and Unit Circle Trig Quiz Answers

Quiz answers on radian angles, unit circle and right triangle trig (Sections 4.1-4.4)

Answers to a first Trig Test

Answers to a first Test in Trig: Graphing Sine Cosine and other trig facts and word problems.

Click on the Green title to see the video.