Question

What is the derivative of `f(x)=sin(-x)-sin(x)`?

Answer 1

`dy/dx = -2cos(x)`

Explanation:

The sine is an odd function, so `sin(-x) = -sin(x)`

So we have

`y = sin(-x)-sin(x) = -sin(x)-sin(x) = -2sin(x)`

Derivating it we have

`dy/dx = -2cos(x)`