Indefinite Integration

Assertion (A) If \(I_n=\int \cot ^n x d x\), then
\(I_6+I_4=\frac{-\cot ^5 x}{5}\)

Reason (R) \(\int \cot ^n x d x=\frac{-\cot ^{n-1} x}{n} -\int \cot ^{n-2} x d x\)