How do I solve the integral of cos^2(x) using trigonometric identities?

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SUMMARY

The integral of cos²(ax) can be solved using the trigonometric identity cos(2x) = 2cos²(x) - 1. By rearranging this identity, cos²(x) can be expressed as (1 + cos(2x))/2. Therefore, the integral ∫cos²(ax)dx simplifies to ∫(1 + cos(2ax))/2 dx, which can be integrated easily to yield (x/2) + (sin(2ax)/(4a)) + C, where C is the constant of integration.

PREREQUISITES
  • Understanding of basic calculus concepts, specifically integration.
  • Familiarity with trigonometric identities, particularly cos(2x).
  • Knowledge of integration techniques for trigonometric functions.
  • Ability to manipulate algebraic expressions involving trigonometric functions.
NEXT STEPS
  • Study the derivation and application of trigonometric identities in calculus.
  • Learn advanced integration techniques, including integration by parts and substitution.
  • Explore the use of definite integrals with trigonometric functions.
  • Practice solving integrals involving other trigonometric functions, such as sin²(x) and tan²(x).
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Students studying calculus, particularly those focusing on integration techniques, as well as educators seeking to enhance their teaching of trigonometric integrals.

Starwatcher16
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Could someone walk me through this one? I know what the answer is, but don't really see how that answer is come by. In the book, it just states the answer, so I guess its something obvious, but the answer still eludes me :(


Homework Equations


\int{Cos^2{(ax)}}dx
 
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Make sure you know your trig identities.

<br /> \cos 2x=2 \cos^2x-1<br />
 

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