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The domain of the function y=sin⁡−1(x−1)+cos⁡−1x−1y = \sin^{-1}(x-1) + \cos^{-1}\sqrt{x-1} is:

Solution

✅ Correct Option: 3

For the function y=sin⁡−1(x−1)+cos⁡−1x−1y = \sin^{-1}(x-1) + \cos^{-1}\sqrt{x-1} to be defined, all parts must work.


The function sin⁡−1\sin^{-1} only accepts inputs between −1-1 and 11 (inclusive).

For sin⁡−1(x−1)\sin^{-1}(x-1):

−1≤(x−1)≤1-1 \leq (x-1) \leq 1

−1+1≤x−1+1≤1+1-1 + 1 \leq x - 1 + 1 \leq 1 + 1

0≤x≤20 \leq x \leq 2

From the first term: x∈[0,2]x \in [0, 2]


For cos⁡−1x−1\cos^{-1}\sqrt{x-1}, there are two conditions:

The square root must be real (non-negative radicand):

x−1≥0x - 1 \geq 0

x≥1x \geq 1

The function cos⁡−1\cos^{-1} only accepts inputs between −1-1 and 11.

Since square roots are always non-negative:

0≤x−1≤10 \leq \sqrt{x-1} \leq 1

x−1≤1\sqrt{x-1} \leq 1

x−1≤1x - 1 \leq 1

x≤2x \leq 2

Combining both conditions: 1≤x≤21 \leq x \leq 2

From the second term: x∈[1,2]x \in [1, 2]


For the entire function to be defined:

First term requires: [0,2][0, 2]

Second term requires: [1,2][1, 2]

The intersection is: [1,2][1, 2]

Therefore, the domain is [1,2][1, 2].

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