MCQ
$\int_0^{\pi /2} {\sqrt {\cos \theta } {{\sin }^3}\theta } \,d\theta = $
  • A
    $\frac{{20}}{{21}}$
  • $\frac{8}{{21}}$
  • C
    $\frac{{ - 20}}{{21}}$
  • D
    $\frac{{ - 8}}{{21}}$

Answer

Correct option: B.
$\frac{8}{{21}}$
b
(b) Let $I = \int_0^{\pi /2} {\sqrt {\cos \theta } } {\sin ^3}\theta \,\,d\theta $

Put $t = \cos \theta \Rightarrow dt = - \sin \theta \,\,d\theta ,$ then

$I =$$ - \int_1^0 {{t^{1/2}}(1 - {t^2})dt = \int_0^1 {({t^{1/2}} - {t^{5/2}})} } $$dt$

$I = $$\left[ {\frac{2}{3}{t^{3/2}} - \frac{2}{7}{t^{7/2}}} \right]_0^1 = \frac{8}{{21}}$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

For any $y \in \mathbb{R}$, let $\cot ^{-1}(y) \in(0, \pi)$ and $\tan ^{-1}(y) \in\left(-\frac{\pi}{2}, \frac{\pi}{2}\right)$. Then the sum of all the solutions of the equation $\tan ^{-1}\left(\frac{6 y}{9-y^2}\right)+\cot ^{-1}\left(\frac{9-y^2}{6 y}\right)=\frac{2 \pi}{3}$ for $0<|y|<3$, is equal to
The direction cosines of the line passing through the two points $(-2,4,-5)$ and $(1,2,3)$ is :
If the polynomial equation $\text{a}_0\text{x}^{\text{n}}+\text{a}_{\text{n}-1}\text{x}^{\text{n}-1}+\text{a}_{\text{n}-2}\text{x}^{\text{n}-2}+...\text{a}_2\text{x}^2+\text{a}_1\text{x}+\text{a}_0=0$ n positive integer,has two different real roots $\alpha$ and $\beta,$ then between $\alpha$ and $\beta,$ the equation $\text{n}\text{a}_{\text{n}}\text{x}^{\text{n}-1}+(\text{n}-1)\text{a}_{\text{n}-1}\text{x}^{\text{n}-2}+...+\text{a}_1=0$ has:
  1. Exactly one root.
  2. Almost one root.
  3. At least one root.
  4. No root.
The function $f(x)=\cot ^{-1} x+x$ increases in the interval
Solution of $\int \sin 3 x d x$ is
If $f : R \rightarrow R$ be a continuous function satisfying

$\int \limits_0^{\pi / 2} f(\sin 2 x) \cdot \sin x d x+\alpha \int \limits_0^{\pi / 4} f(\cos 2 x) \cdot \cos x d x=0$then $\alpha$ is equal to

The maximum value of $f(x) = {x \over {4 + x + {x^2}}}$ on $[ - 1,\,1]$ is
If the constraints in a linear programming problem are changed
The system of equation x + y + z = 2, 3x − y + 2z = 6 and 3x + y + z = −18 has:
  1. A unique solution.
  2. No solution.
  3. An infinite number of solutions.
  4. Zero solution as the only solution.
A fair $n(n > 1)$ faces die is rolled repeatedly until a number less than $n$ appears. If the mean of the number of tosses required is $\frac{ n }{9}$, then $n$ is equal to