Trigonometric ratios of supplementary angles Trigonometric identities Problems on trigonometric identities Trigonometry heights and distances. Each equation will require different techniques, but there are a few tips to keep in mind when verifying trigonometric identities. Power Rule: d dx (xn) = nxn 1 3. Ex. Verifying trig identities can require lots of different math techniques, including FOIL, distribution, substitutions, and conjugations. Derivatives Cheat Sheet Derivative Rules 1. 1 + cos x = esc x + cot x sinx Essential Identities. The more basic formulas you have memorized, the faster you will be. In trigonometry, an identity is a trigonometric equation that is held to be true. In this lesson we will continuously review the fundamental identities and the steps we learned previously for proving trig identities in order to tackle 15 classic examples that will give you all the skills necessary to handling even the hardest problem. Trigonometric ratios of complementary angles. Trig Cheat Sheet Definition of the Trig Functions Right triangle definition For this definition we assume that 0 2 p <