Exercise 43 Page 796

Let's plot the given points on a coordinate plane and graph the triangle.

The area of a triangle is half the product of a base and its corresponding height. Notice that we can find the length of the base and the height of our parallelogram by counting the squares on the coordinate plane.

We can see that the length of the base $b$ is $7$ and the length of the height is $5.$ Now, we can substitute these measures into the formula for the area of a triangle. The area of the triangle is $17.5$ square units.