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MA L 7.2 Verifying Trigonometric Identities Make the left side equal the right. Hints for Proving Identities • Select the more complex side of the = sign to work on. • Use double & half-angle formulas is necessary to get all trig functions of the same angle (x) • Carry out any algebraic manipulations, such as adding, subtracting, multiplying, or factoring. • If given rational expressions, get LCD. • Converting all expressions to sines and cosines is often helpful. • If working on the left side, constantly refer to the right and see how you can get something on the left to match the right. • Try Something! Put your pencil to work and get involved. There is usually more than one method. If you find your equation getting further complicated, start over with a new approach. Let’s begin with what we already know. The Pythagorean theorem yields… Here are three KEY techniques: Replacing Replacing sin x with 1 cos x 2 2 cos2 x with 1 2sin x Using the Quadratic Formula 2 1=1 Example 333 3