Very easy definite integral question

Evaluate the integral below by interpreting it in terms of areas. In other words, draw a picture of the region the integral represents, and find the area using high school geometry. http://euler.vaniercollege.qc.ca/web...53ef350ee1.png I don't know why, but I'm messing this up. I do x = 3 (so y = 0) and x = -3 (so

) to get a graph that looks like a triangle. Using simply geometry to find the answer, I do 6 (the base) *

(the height) divided by 2 to get

. Which is wrong.

But why?