Use the reduction formula:
∫sin^n(x) dx = − 1/n cos(x) sin^n − 1(x) + n − 1/n ∫sin^n − 2(x) dx, where n > _ 2 is an integer to determine which of the following reduction formulas is correct.
∫π/2 0 sin^n (x) dx = n+2 / n ∫π/2 0 sin^ n + 1 (x) dx
∫π/2 0 sin^n (x) dx = n+1 / n ∫π/2 0 sin^ n + 2 (x) dx
∫π/2 0 sin^n (x) dx = n-1 / n ∫π/2 0 sin^ n - 2 (x) dx
∫π/2 0 sin^n (x) dx = n-2 / n ∫π/2 0 sin^ n - 1 (x) dx