Hey. So, I'm having trouble figuring out how to solve this integral. And I would really appreciate it if someone could help me.

Okay, so I know I need to split the integral because it is an absolute value. But I'm unsure of what values I need to use to do that. Can I just pick any value I want?

Mr F says: Draw the graph first by reflecting in the x-axis the parts of the graph of y = sin x that are below the x-axis. Then it should be quite obvious what the intervals need to be.
Also, I've been working on this problem, can someone tell me if I am approaching it correctly?

Here is what I have thus far:

..and that's all I have so far, but I'm not really sure what I need to do. Or if I'm even doing it correctly.

Mr F says: It's almost OK (see the mistakes I corrected in red). Obviously the next step is to calculate the derivatives ....
Thanks!!!!