MCQ
The principal solution of $\cos ^{-1}\left(\cos \left(\frac{7 \pi}{6}\right)\right)$ is
  • A
    $\frac{7 \pi}{6}$
  • $\frac{5 \pi}{6}$
  • C
    $\frac{\pi}{6}$
  • D
    $\frac{11 \pi}{6}$

Answer

Correct option: B.
$\frac{5 \pi}{6}$
$\cos ^{-1}\left(\cos \left(\frac{7 \pi}{6}\right)\right)=\cos ^{-1}\left(\cos \left(\pi+\frac{\pi}{6}\right)\right)$
$=\cos ^{-1}\left(-\cos \left(\frac{\pi}{6}\right)\right)$
$=\cos ^{-1}\left(\cos \left(\pi-\frac{\pi}{6}\right)\right)=\cos ^{-1}\left(\cos \left(\frac{5 \pi}{6}\right)\right)=\frac{5 \pi}{6}$

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

The value(s) of $\int_0^1 \frac{x^4(1-x)^4}{1+x^2} d x$ is (are)
Let $f: R \rightarrow R$ be defined as

$f(x)=\left\{\begin{array}{ll}\frac{x^{3}}{(1-\cos 2 x)^{2}} \log _{e}\left(\frac{1+2 x e^{-2 x}}{\left(1-x e^{-x}\right)^{2}}\right), & x \neq 0 \\ \,\alpha & , x=0\end{array}\right.$ If $\mathrm{f}$ is continuous at $\mathrm{x}=0$, then $\alpha$ is equal to :

The probability of men getting a certain disease is $\frac{1}{2}$ and that of women getting the same disease is $\frac{1}{5}$. The blood test that identifies the disease gives the correct result with probability $\frac{4}{5}$. Suppose a person is chosen at random from a group of $30$ males and $20$ females, and the blood test of that person is found to be positive. What is the probability that the chosen person is a man?
Differential coefficient of ${\tan ^{ - 1}}\left( {{x \over {1 + \sqrt {1 - {x^2}} }}} \right)$ w.r.t ${\sin ^{ - 1}}x,$ is
If $\omega $ be a complex cube root of unity, then $\left| {\,\begin{array}{*{20}{c}}1&\omega &{ - {\omega ^2}/2}\\1&1&1\\1&{ - 1}&0\end{array}\,} \right| = $
Integrating factor of the differential equation $\left(1-x^2\right) \frac{d y}{d x}-x y=1$ is
If $\overrightarrow{ x }$ and $\overrightarrow{ y }$ be two non-zero vectors such that $|\overrightarrow{ x }+\overrightarrow{ y }|=|\overrightarrow{ x }|$ and $2 \overrightarrow{ x }+\lambda \overrightarrow{ y }$ is perpendicular to $\overrightarrow{ y },$ then the value of $\lambda$ is
If $c$ is any arbitrary constant, then $\int {{2^{{2^{{2^x}}}}}{2^{{2^x}}}{2^x}dx} $ is equal to
The shortest distance between the lines $r = (3i - 2j - 2k) + it$ and $r = i - j + 2k + js$ ($t$ and $s$ being parameters) is
In a $\triangle\text{ABC},$ if C is a right angle, then $\tan^{-1}\Big(\frac{\text{a}}{\text{b}+\text{c}}\Big)+\tan^{-1}\Big(\frac{\text{b}}{\text{c}+\text{b}}\Big)=$