Techniques for Evaluating Trigonometric Integrals Involving Sine, Cosine, Tangent, and Secant
This guide offers strategies for integrating trigonometric functions, specifically sine, cosine, tangent, and secant. For odd powers, use substitutions to express them as a product of a single power and an even power, then apply relevant trigonometric identities to convert the even power. For even powers, utilize double-angle formulas and similar substitutions for simplification. Whether working with sine, cosine, tangent, or secant, the systematic approach described will aid in tackling complex integrals efficiently and accurately.
Techniques for Evaluating Trigonometric Integrals Involving Sine, Cosine, Tangent, and Secant
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Presentation Transcript
Section 8.2 Trigonometric Integrals
For INTEGRALS OFSINE AND COSINE • If n is odd, write as a single power times an even power. Convert the even power to the other function using cos2x+ sin2 x =1. Then use u-substitution. • If n is even, convert to cos 2x using the double-angle formula for cosine.
For INTEGRALS INVOLVING SINE AND COSINE (CONTINUED) • If m or n odd, convert the odd power to a power of one times an even power. Then convert the even power to the other function. Finally, use u-substitution. • If both m and n are even, convert to cos2x using the double-angle formula for cosine.
INTEGRALS INVOLVING TANGENT • If n is odd, convert to a power of one times an even power. Convert the even power using tan2 x + 1 = sec 2x. Then use u-substitution. • If n is even, convert to a power of 2 times an even power. Convert the power of two as above. Then use u-substitution. For ∫ tannx dx
INTEGRALS INVOLVING SECANT AND TANGENT • If n is even and m is any number, write secn x as a power of two times an even power. Covert the even power using tan2 x + 1 = sec2 x. Then use u-substitution. • If m is odd and n is any number, convert tanm x to a single power times an even power. Convert the even power using tan2 x + 1 = sec2 x. Then use u-substitution. For ∫ tanmx secn x dx
INTEGRALS INVOLVING SINE AND COSINE (CONCLUDED) For use the trigonometric identities on the bottom of page 501 of the text.