If sin⁻¹(x-1)+cos⁻¹(x-3)+tan⁻¹ ((x)/(2-x²))=cos⁻¹k+π, then what is the value of k?
1
−1/√2
1/√2
None of these
Correct answer: 1/√2
Solution
sin^-1(x-1) needs x in [0,2]; cos^-1(x-3) needs x in [2,4]; their intersection is x=2. At x=2: pi/2 + pi + tan^-1(2/(2-4)) = pi/2 + pi - pi/4 = 5pi/4. Setting = cos^-1(k) + pi gives cos^-1(k) = pi/4, so k = 1/sqrt(2).