Question

How do you find the derivative of `cos(pi x)`?

Answer 1

`(dy)/(dx)=-pisin(pix)`

Explanation:

Let,

`y=cos(pix)`

Using Chain Rule :

`:.(dy)/(dx)=-sin(pix)d/(dx)(pix)`

`:.(dy)/(dx)=-sin(pix)(pi)`

`:.(dy)/(dx)=-pisin(pix)`