Questions number 19 and 20 are Assertion and Reason based questions. Two statements are given, one labelled Assertion (A) and the other labelled…

Questions number $\displaystyle 19$ and $\displaystyle 20$ are Assertion and Reason based questions. Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below. Assertion (A): $\displaystyle \int \frac{1}{\sqrt{9-\mathrm{x}^2}} \mathrm{dx}=\sin ^{-1} \frac{\mathrm{x}}{3}+\mathrm{C}$ Reason (R): $\displaystyle \int \frac{1}{\sqrt{\mathrm{a}^2-\mathrm{x}^2}} \mathrm{dx}=\sin ^{-1} \frac{\mathrm{x}}{\mathrm{a}}+\mathrm{C}$