Sum and Difference Identities & Formulas Sine,Cosine,Tangent

This trigonometry tutorial explains how to use the sum and difference identities and formulas to evaluate exact values by using the sum and difference formulas for an angle not found on the unit circle.
This video is long so this guide may help.
00:00 Introduction to sum and difference formulas.
00:15 Find the sum of 105 degrees which is not on the unit circle.
01:17 Take a look at sum and difference formulas.
09:44 Find a sum or difference from the unit circle that is equal to 5 pi over 12
22:44 Verify the identity.
25:24 Ratio of sides of triangles.
34:33 Evaluate and write the trig value.
37:19 Verify using sum and difference.
41:08 Write as an algebraic expression.
44:57 Find all of the solutions of the equation in the interval 0, to2 pi