# What is the amplitude of #f(x)=4sin(x)cos(x)#?

##### 1 Answer

Feb 3, 2015

The answer is:

The amplitude of a periodic function is the numer that multiply the function itself.

Using the double-angle formula of sinus, that says:

we have:

So the **amplitude** is

This is the sinus function:

graph{sinx [-10, 10, -5, 5]}

This is the

graph{sin(2x) [-10, 10, -5, 5]}

and this is the

graph{2sin(2x) [-10, 10, -5, 5]}