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int(cos^(3)xdx)/(sin^(2)x-4)

cos3xdxsin2x4 \int \frac{\cos ^{3} x d x}{\sin ^{2} x-4}

Full solution

Q. cos3xdxsin2x4 \int \frac{\cos ^{3} x d x}{\sin ^{2} x-4}
  1. Identify Integral: Identify the integral to be solved.\newlineWe need to evaluate the integral of the function cos3(x)sin2(x)4\frac{\cos^3(x)}{\sin^2(x)-4} with respect to xx.
  2. Simplify if Possible: Simplify the integral if possible.\newlineThe integral does not simplify easily due to the complex relationship between the numerator and the denominator. We may need to consider a substitution that relates sin(x)\sin(x) and cos(x)\cos(x) or use trigonometric identities to simplify the expression.
  3. Consider Substitution: Consider a substitution.\newlineLet u=sin(x)u = \sin(x), then du=cos(x)dxdu = \cos(x)dx. This substitution will help us rewrite the integral in terms of uu, which might simplify the expression.
  4. Rewrite Using Substitution: Rewrite the integral using the substitution.\newlineThe integral becomes cos2(x)cos(x)dxu24\int\frac{\cos^2(x)\cos(x)\,dx}{u^2-4}. Since we have du=cos(x)dxdu = \cos(x)\,dx, we can replace cos(x)dx\cos(x)\,dx with dudu. However, we still have a cos2(x)\cos^2(x) term in the numerator, which we need to express in terms of uu.
  5. Use Trig Identity: Use a trigonometric identity to express cos2(x)\cos^2(x) in terms of uu. We know that sin2(x)+cos2(x)=1\sin^2(x) + \cos^2(x) = 1, so cos2(x)=1sin2(x)\cos^2(x) = 1 - \sin^2(x). Substituting u=sin(x)u = \sin(x), we get cos2(x)=1u2\cos^2(x) = 1 - u^2.
  6. Substitute with uu: Substitute cos2(x)\cos^2(x) with 1u21 - u^2 in the integral.\newlineThe integral now becomes (1u2)duu24\int\frac{(1 - u^2)\,du}{u^2-4}.
  7. Simplify Integral: Simplify the integral.\newlineWe can now integrate term by term. The integral becomes duu24\int\frac{du}{u^2-4} - u2duu24\int\frac{u^2du}{u^2-4}.
  8. Evaluate First Term: Evaluate the first term of the integral.\newlineThe first term duu24\int\frac{du}{u^2-4} is a standard integral that can be solved using partial fractions. However, I realize there is a mistake in the previous steps. We have not accounted for the cos3(x)\cos^3(x) correctly in our substitution. We only replaced cos(x)dx\cos(x)dx with dudu, but we still have an extra cos2(x)\cos^2(x) term that needs to be accounted for. This is a math error.

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