We need to evaluate the integral:
∫ [sec⁻¹((x + 1) / (x - 1))] + [sin⁻¹((x - 1) / (x + 1))] dx
Step 1: Define Functions
Let:
I = ∫ [sec⁻¹((x + 1) / (x - 1))] + [sin⁻¹((x - 1) / (x + 1))] dx
Step 2: Check for Possible Simplifications
We analyze the two inverse trigonometric functions separately.
Expression 1: sec⁻¹((x + 1) / (x - 1))
For the given function sec⁻¹(y), we know that:
sec⁻¹(y) + sin⁻¹(1/y) = π/2, for y > 1
If we set y = (x + 1) / (x - 1), then its reciprocal is:
1/y = (x - 1) / (x + 1)
Thus,
sin⁻¹((x - 1) / (x + 1)) = π/2 - sec⁻¹((x + 1) / (x - 1))
Step 3: Substituting the Identity
From the identity above, we substitute in our integral:
I = ∫ [sec⁻¹((x + 1) / (x - 1))] + [π/2 - sec⁻¹((x + 1) / (x - 1))] dx
This simplifies to:
I = ∫ [π/2] dx
Step 4: Final Integration
Since π/2 is a constant, its integral is straightforward:
I = (π/2) ∫ dx
I = (π/2) x + C
Final Answer:
I = (π/2) x + C