Question
Download Solution PDFIf ∫(cos x - sin x)/\(\rm \sqrt{8-\sin 2x)}\) dx = a sin-1(sin x + cos x)/b + c where c is a constant of integration, then the ordered pair (a, b) is equal to:
Answer (Detailed Solution Below)
Option 2 : (1, 3)
Detailed Solution
Download Solution PDFConcept:
\(\int\frac{dx}{\sqrt{a^2-x^2}}=\sin^{-1}\left(\frac{x}{a}\right)+C\)
Calculation:
Given,
∫(cos x - sin x)/\(\rm \sqrt{8-\sin 2x)}\) dx = a sin-1(sin x + cos x)/b + c
Let I = ∫(cos x - sin x)/\(\rm \sqrt{8-\sin 2x)}\) dx
Put sin x + cos x = t ⇒ (cos x -sin x ) dx = dt
Also, 1 + sin 2x = t2
⇒ I = ∫dt/√(8-(t2-1))
= ∫dt/(9-t2)
= sin-1 (t/3) + c
= sin-1(sin x + cos x)/3 + c = a sin-1(sin x + cos x)/b + c
⇒ a = 1 and b = 3
∴ The the ordered pair (a, b) is equal to (1, 3).
The correct answer is Option 2.