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11sinxdx\int \frac{1}{1-\sin x} \, dx

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Q. 11sinxdx\int \frac{1}{1-\sin x} \, dx
  1. Apply Weierstrass substitution: Use the Weierstrass substitution to simplify the integral. Let t=tan(x2)t = \tan(\frac{x}{2}), then sin(x)=2t1+t2\sin(x) = \frac{2t}{1 + t^2} and dx=21+t2dtdx = \frac{2}{1 + t^2} dt.
  2. Substitute sin(x)\sin(x) and dxdx: Substitute sin(x)\sin(x) and dxdx in the integral.11sinxdx=112t1+t221+t2dt\int\frac{1}{1 - \sin x}\,dx = \int\frac{1}{1 - \frac{2t}{1 + t^2}} \cdot \frac{2}{1 + t^2}\,dt
  3. Simplify the integrand: Simplify the integrand. 112t1+t221+t2dt=1+t21+t22t21+t2dt=21t2dt\int\frac{1}{1 - \frac{2t}{1 + t^2}} \cdot \frac{2}{1 + t^2}\,dt = \int\frac{1 + t^2}{1 + t^2 - 2t} \cdot \frac{2}{1 + t^2}\,dt = \int\frac{2}{1 - t^2}\,dt
  4. Decompose into partial fractions: Decompose the integrand into partial fractions. \newline21t2\frac{2}{1 - t^2} can be written as A1t+B1+t\frac{A}{1 - t} + \frac{B}{1 + t}.\newlineSolving for AA and BB, we get A=1A = 1 and B=1B = 1.
  5. Write in terms of partial fractions: Write the integral in terms of the partial fractions. \int\frac{\(2\)}{\(1\) - t^\(2\)}\,dt = \int\frac{\(1\)}{\(1\) - t}\,dt + \int\frac{\(1\)}{\(1\) + t}\,dt
  6. Integrate each term separately: Integrate each term separately.\(\newline11tdt=ln1t+C1\int\frac{1}{1 - t}\,dt = -\ln|1 - t| + C_1\newline11+tdt=ln1+t+C2\int\frac{1}{1 + t}\,dt = \ln|1 + t| + C_2
  7. Combine the two integrals: Combine the two integrals. 21t2dt=ln1t+ln1+t+C=ln1+tln1t+C\int \frac{2}{1 - t^2}\,dt = -\ln|1 - t| + \ln|1 + t| + C = \ln|1 + t| - \ln|1 - t| + C
  8. Substitute back for t: Substitute back for t = tan(x2)\tan(\frac{x}{2}).\newlineln1+tan(x2)ln1tan(x2)+C=ln(1+tan(x2))(1tan(x2))+C\ln|1 + \tan(\frac{x}{2})| - \ln|1 - \tan(\frac{x}{2})| + C = \ln|\frac{(1 + \tan(\frac{x}{2}))}{(1 - \tan(\frac{x}{2}))}| + C
  9. Simplify using trigonometric identities: Simplify the expression using trigonometric identities.\newline\ln\left|\frac{\(1\) + \tan(\frac{x}{\(2\)})}{\(1\) - \tan(\frac{x}{\(2\)})}\right| + C = \ln\left|\frac{(\(1\) + \tan(\frac{x}{\(2\)}))^\(2\)}{(\(1\) - \tan(\frac{x}{\(2\)}))(\(1\) + \tan(\frac{x}{\(2\)}))}\right| + C\(\newline= \ln\left|\frac{(11 + \tan(\frac{x}{22}))^22}{11 - \tan^22(\frac{x}{22})}\right| + C\newline= \ln\left|\frac{11 + \sin(x)}{11 - \sin(x)}\right| + C
  10. Check final expression: Check if the final expression is correct.\newlineThe final expression ln(1+sin(x))(1sin(x))+C\ln\left|\frac{(1 + \sin(x))}{(1 - \sin(x))}\right| + C is the antiderivative of 1(1sinx)\frac{1}{(1 - \sin x)}, which answers the question prompt.

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