MCQ
$\cos ({\tan ^{ - 1}}x) = $
  • A
    $\sqrt {1 + {x^2}} $
  • $\frac{1}{{\sqrt {1 + {x^2}} }}$
  • C
    $1 + {x^2}$
  • D
    None of these

Answer

Correct option: B.
$\frac{1}{{\sqrt {1 + {x^2}} }}$
b
(b) Let $\theta = {\tan ^{ - 1}}x\,\, \Rightarrow \,\,x = \tan \theta $

$\therefore \,\,\cos \theta = \frac{1}{{\sqrt {1 + {{\tan }^2}\theta } }} = \frac{1}{{\sqrt {1 + {x^2}} }}$

Hence $\cos \theta = \cos \,({\tan ^{ - 1}}x) = \frac{1}{{\sqrt {1 + {x^2}} }}$.

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

Let $f : R \rightarrow R$ and $g : R \rightarrow R$ be defined as $f(x)=\left\{\begin{array}{ll}x+a, & x<0 \\ |x-1|, & x \geq 0\end{array}\right.$ and $g(x)=\left\{\begin{array}{cc}x+1, & x<0 \\ (x-1)^{2}+b, & x \geq 0\end{array}\right.$ where $a , b$ are non-negative real numbers. If $(gof)\,( x )$ is continuous for all $x \in R$, then $a + b$ is equal to ...... .
The volume of a sphere is increasing at 3cm3/sec. The rate at which the radius increases when radius is 2cm, is:

  1. $\frac{3}{32\pi}\text{cm}/\text{sec}.$   

  2. $\frac{3}{16\pi}\text{cm}/\text{sec}.$

  3. ​​​​​​​$\frac{3}{48\pi}\text{cm}/\text{sec}.$​​​​​​​

  4. $\frac{1}{24\pi}\text{cm}/\text{sec}.$

If d is the determinant of a square matrix A of order n, then the determinant of its adjoint is:
  1. dn
  2. dn-1
  3. dn+1
  4. d
The value of $\int\frac{\cos2\text{x}}{{\cos}{\text{ x}}}\text{dx}$ is equal to:
  1. $2\sin\text{x}-\ell\text{ n }\mid\sec\text{x}+\tan\text{x}\mid+\text{ c}$
  2. $2\sin\text{x}-\ell\text{ n }\mid\sec\text{x}-\tan\text{x}\mid+\text{ c}$
  3. $2\sin\text{x}+\ell\text{ n }\mid\sec\text{x}+\tan\text{x}\mid+\text{ c}$
  4. $3\sin\text{x}-\ell\text{ n }\mid\sec\text{x}+\tan\text{x}\mid+\text{ c}$
Suppose $a_1, a_2, .......$ real numbers, with $a_1 \ne 0$. If $a_1, a_2, a_3, ..........$ are in $A.P$. then
$\left|\begin{array}{cc}\cos \theta & -\sin \theta \\ \sin \theta & \cos \theta\end{array}\right|=$
$\int_0^{\pi /2} {\frac{{\sin x\cos x}}{{1 + {{\sin }^4}x}}\,dx = } $
If the matrix AB is zero, then:
  1. It is not necessary that either A = 0 or, B = 0
  2. A = 0 or B = 0
  3. A = 0 and B = 0
  4. All the above statements are wrong
If the points $({x_1},{y_1}),({x_2},{y_2})$ and $({x_3},{y_3})$ are collinear, then the rank of the matrix $\left[ {\begin{array}{*{20}{c}}{{x_1}}&{{y_1}}&1\\{{x_2}}&{{y_2}}&1\\{{x_3}}&{{y_3}}&1\end{array}} \right]$ will always be less than
For $3 \times 3$ matrices $M$ and $N$, which of the following statement$(s)$ is (are) $NOT$ correct?

$(A)$ $N ^{\top} M N$ is symmetric or skew symmetric, according as $M$ is symmetric or skew symmetric

$(B)$ $M N-N M$ is skew symmetric for all symmetric matrices $M$ and $N$

$(C)$ $M N$ is symetric for all symmetric matrices $M$ and $N$

$(D)$ $(\operatorname{adj} M)(\operatorname{adj} N)=\operatorname{adj}(M N)$ for all invertible matrices $M$ and $N$