MCQ
${\tan ^{ - 1}}\left( {\frac{1}{4}} \right) + {\tan ^{ - 1}}\left( {\frac{2}{9}} \right) = $
  • $\frac{1}{2}{\cos ^{ - 1}}\left( {\frac{3}{5}} \right)$
  • B
    $\frac{1}{2}{\sin ^{ - 1}}\left( {\frac{3}{5}} \right)$
  • C
    $\frac{1}{2}{\tan ^{ - 1}}\left( {\frac{3}{5}} \right)$
  • D
    None of these

Answer

Correct option: A.
$\frac{1}{2}{\cos ^{ - 1}}\left( {\frac{3}{5}} \right)$
a
(a) ${\tan ^{ - 1}}\frac{1}{4} + {\tan ^{ - 1}}\frac{2}{9} = {\tan ^{ - 1}}\left( {\frac{{(1/4) + (2/9)}}{{1 - (1/4) \times (2/9)}}} \right)$

$={\tan ^{ - 1}}\left( {\frac{1}{2}} \right) = \frac{1}{2}.2{\tan ^{ - 1}}\left( {\frac{1}{2}} \right) = \frac{1}{2}{\tan ^{ - 1}}\frac{{2(1/2)}}{{1 - (1/4)}}$

$ = \frac{1}{2}{\tan ^{ - 1}}\frac{4}{3} = \frac{1}{2}{\cos ^{ - 1}}\frac{3}{5}$.

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

If $\int\limits^\alpha_0\frac{1}{1+4\text{x}^2}\text{ dx}=\frac{\pi}{8},$ then a equals:
  1. $\frac{\pi}{2}$
  2. $\frac{1}{2}$
  3. $\frac{\pi}{4}$
  4. $1$
Choose the correct answer from the given four options.
If $|\text{x}|\leq1,$ then $2\tan^{-1}\text{x}+\sin^{-1}\Big(\frac{2\text{x}}{1+\text{x}^2}\Big)$ is equal to:
  1. $4\tan^{-1}\text{x}$
  2. $0$
  3. $\frac{\pi}{2}$
  4. $\pi$
The maximum value of f = 4x + 3y subject to constraints $\text{x}\geq0,$ $\text{y}\geq0,$ $2\text{x}+3\text{y}\leq18;\text{x}+\text{y}\geq10$ is:
The first derivative of the function $(\sin 2x\cos 2x\cos 3x + {\log _2}{2^{x + 3}})$ with respect to $ x$  at $x = \pi $ is
If $\text{y}=\text{ax}^{\text{n+1}}+\text{bx}^{-\text{n}}$ Then $\text{x}^2\frac{\text{d}^2\text{y}}{\text{dx}^2}$ =
  1. n(n - 1) y
  2. n(n + 1) y
  3. ny
  4. n2y
If the force $\overrightarrow F = i + 2j + 3k$ moves from $i + j - k$ to $2i - j + k,$ then work done will be represented by
The value of the integral $\int_{-\pi}^\pi \frac{\cos ^2 x}{1+a^x} d x$, where $a > 0$, is
Let $X$ and $Y$ be two events such that $P(X \mid Y)=\frac{1}{2}, P(Y \mid X)=\frac{1}{3}$ and $P(X \cap Y)=\frac{1}{6}$. Which of the following is (are) correct?

$(A)$ $P(X \cup Y)=\frac{2}{3}$

$(B)$ $X$ and $Y$ are independent

$(C)$ $X$ and $Y$ are not independent

$(D)$ $P\left(X^C \cap Y\right)=\frac{1}{3}$

If the function $f(x)\, = \left\{ {\begin{array}{*{20}{c}}{ - x,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x < 1\,\,\,\,}\\{a + {{\cos }^{ - 1}}(x + b),\,\,\,\,\,\,\,\,\,1 \le x \le 2} \end{array}} \right.$  is differentiable at $x = 1 ,$ then $\frac {a}{b}$ is equal to 
If any matrix has order $m \times n$, then number of elements :