Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Inverse Trigonometric Functions

Question:

Match List-I with List-II regarding the value of the following.

List-I List-II
(A) $cos^{-1}(cos\frac{7\pi }{6})$ (I) $\frac{\pi }{2}$
(B) $cos^{-1}(cos\frac{5\pi }{4})$ (II) $\frac{\pi }{4}$
(C) $sin^{-1}\frac{4}{5}+2tan^{-1}\frac{1}{3}$ (III) $\frac{5\pi }{6}$
(D) $tan^{-1}\frac{x}{y}-tan^{-1}\frac{x-y}{x+y}$ (IV) $\frac{3\pi }{4}$

Choose the correct answer from the options given below:

Options:

(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

(A)-(II), (B)-(I), (C)-(IV), (D)-(III)

(A)-(III), (B)-(IV), (C)-(I), (D)-(II)

(A)-(I), (B)-(II), (C)-(III), (D)-(IV)

Correct Answer:

(A)-(III), (B)-(IV), (C)-(I), (D)-(II)

Explanation:

The correct answer is Option (3) → (A)-(III), (B)-(IV), (C)-(I), (D)-(II)

(A) $\cos^{-1}(\cos\frac{7\pi }{6})=\cos^{-1}(-\frac{\sqrt{3}}{2})$

$=\pi - \frac{\pi}{6}=\frac{5\pi }{6}$ (III)

(B) $\cos^{-1}(\cos\frac{5\pi }{4})=\cos^{-1}(-\frac{1}{\sqrt{2}})$

$=\pi - \frac{\pi}{4}=\frac{3\pi }{4}$ (IV)

(C) $\sin^{-1}\frac{4}{5}+2\tan^{-1}\frac{1}{3}$

$=\tan^{-1}\frac{4}{3}+\tan^{-1}\frac{2×\frac{1}{3}}{1-\frac{1}{9}}$

$=\tan^{-1}\frac{4}{3}+\tan^{-1}\frac{3}{4}=\frac{\pi}{2}$ (I)

(D) $\tan^{-1}\frac{x}{y}-\tan^{-1}\frac{x-y}{x+y}$

$=\tan^{-1}\frac{x}{y}-\tan^{-1}\frac{\frac{x}{y}-1}{\frac{x}{y}+1}=\tan^{-1}\frac{x}{y}-\tan^{-1}\frac{x}{y}+\tan^{-1}1=\frac{\pi}{4}$ (II)