First we need to find the base and height of the triangle. We can see that the base goes from 3 to 11 on the coordinate plane. If we take 11 - 3, we get 8.
8 is our base. We can also see that the height goes from 3 to 12. 12 - 3 is 9, so our height is 9.
The formula for a triangle is (1/2)bh so 8 x 9 is 72, and 72 times 1/2 is 36.
The area of the triangle on the coordinate plane is 36 units
