Question

pls derive this . r=cosx cot x

Answer 1

You must use product rule:

(dr/dx) = cos(x) * dx/dr(cot(x)) + (dx/dr)cos(x) * cot(x)

r' = cos(x) * -csc²(x) + -sin(x) * cot(x)

If simplification is needed:

r' = -cos(x) * $\frac{1}{sin^{2}(x)}$ - sin(x) * $\frac{cos(x)}{sin(x)}$

r' = $\frac{-cos(x)}{sin^{2}(x)}$ - cos(x)

There are other forms. Good luck!