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Match List-I with List-II

List-IList-II
(A) sin⁡−1(−1)\sin^{-1}(-1)(I) 5π6\frac{5\pi}{6}
(B) cot⁡−1(−1)\cot^{-1}(-1)(II) −π2\frac{-\pi}{2}
(C) sec⁡−1(−23)\sec^{-1}\left(\frac{-2}{\sqrt{3}}\right)(III) π4\frac{\pi}{4}
(D) tan⁡−1(1)\tan^{-1}(1)(IV) 3π4\frac{3\pi}{4}

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 1

For sin⁡−1(−1)\sin^{-1}(-1):

Principal range for sin⁡−1\sin^{-1} is [−π2,π2]\left[-\frac{\pi}{2}, \frac{\pi}{2}\right]

At angle −π2\frac{-\pi}{2}, sin⁡(−π2)=−1\sin\left(\frac{-\pi}{2}\right) = -1

Therefore sin⁡−1(−1)=−π2\sin^{-1}(-1) = \frac{-\pi}{2} → (II)


For cot⁡−1(−1)\cot^{-1}(-1):

Principal range for cot⁡−1\cot^{-1} is (0,π)(0, \pi)

Since cot⁡(θ)=−1\cot(\theta) = -1, then tan⁡(θ)=−1\tan(\theta) = -1

In the range (0,π)(0, \pi), tangent is negative in the second quadrant.

At angle 3π4\frac{3\pi}{4}, tan⁡(3π4)=−1\tan\left(\frac{3\pi}{4}\right) = -1

Therefore cot⁡−1(−1)=3π4\cot^{-1}(-1) = \frac{3\pi}{4} → (IV)


For sec⁡−1(−23)\sec^{-1}\left(\frac{-2}{\sqrt{3}}\right):

Principal range for sec⁡−1\sec^{-1} is [0,π][0, \pi] excluding π2\frac{\pi}{2}

sec⁡(θ)=−23\sec(\theta) = \frac{-2}{\sqrt{3}} means cos⁡(θ)=−32\cos(\theta) = \frac{-\sqrt{3}}{2}

Cosine is negative in the second quadrant.

At angle 5π6\frac{5\pi}{6}, cos⁡(5π6)=−32\cos\left(\frac{5\pi}{6}\right) = \frac{-\sqrt{3}}{2}

Therefore sec⁡−1(−23)=5π6\sec^{-1}\left(\frac{-2}{\sqrt{3}}\right) = \frac{5\pi}{6} → (I)


For tan⁡−1(1)\tan^{-1}(1):

Principal range for tan⁡−1\tan^{-1} is (−π2,π2)\left(-\frac{\pi}{2}, \frac{\pi}{2}\right)

At angle π4\frac{\pi}{4}, tan⁡(π4)=1\tan\left(\frac{\pi}{4}\right) = 1

Therefore tan⁡−1(1)=π4\tan^{-1}(1) = \frac{\pi}{4} → (III)


Final matching:

FunctionValueMatches
(A) sin⁡−1(−1)\sin^{-1}(-1)−π2\frac{-\pi}{2}(II)
(B) cot⁡−1(−1)\cot^{-1}(-1)3π4\frac{3\pi}{4}(IV)
(C) sec⁡−1(−23)\sec^{-1}\left(\frac{-2}{\sqrt{3}}\right)5π6\frac{5\pi}{6}(I)
(D) tan⁡−1(1)\tan^{-1}(1)π4\frac{\pi}{4}(III)

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

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