Displacement problem

[temaire]

Homework Statement

http://img52.imageshack.us/img52/5412/displacement.jpg [Broken]

The Attempt at a Solution

First I calculated the equation for the line using point-slope form. I got y = 3x-9. Then I found angula velocity at 8 seconds, which turned out to be 15 rad/s. Then I drew the complete graph and calculated area for the top triangle and the bottom triangle. For the top triangle I got a distance of 37.5 rad and for the bottome triangle I got a distance of 13.5 rad. To calculate displacement, I subtracted the area of the bottome triangle to the area of the top triangle and got 24 rad. Is this correct?

 

[Galileo]

Yes, that's correct.