# What is the net area between #f(x) = cos2x-xsinx # and the x-axis over #x in [0, 3pi ]#?

##### 1 Answer

Apr 13, 2018

The net area between

#### Explanation:

Using the DI method (an easier way to understand integration by parts):

Multiply the diagonals with the appropriate sign, and add them (and don't forget the negative sign in front of the integral from before):

That is the net area under the curve. Hope this helped!