(c) $\int_{}^{}{\cos{\left\lbrack 2\cot^{- 1}\sqrt{\frac{1 - x}{1 + x}} \right\rbrack\ dx}}$ $= \int_{}^{}{\cos{\lbrack\cos^{- 1}{( - x)\rbrack dx}}}$ $= \int_{}^{}{( - x)dx = - \frac{x^{2}}{2} + c}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.