Note:- 1) If y = cotx ; then dy/dx = `-cosec^2(x)`
` `
2) If y = cosecx ; then dy/dx = -cosecx*cotx
Now,
`f(x) = y = cotx`
differentiating
`f'(x) = y' = -cosec^2(x)`
differentiating
`f''(x) = 2cosecx*cosecx*cotx`
or, `f''(x) = y'' = 2cotx*cosec^2x`
Math