And then the fourth trapezoid is going to look like that. And then finally you have the fifth trapezoid. So let's calculate the area of each of these, and then we will have our approximation for the area under the curve. So let's do trapezoid, or I really should say triangle, this first shape, whatever you want to call it. What is the area of that going to be? Well, the area of a trapezoid, and you'll see this will just turn into the area of a triangle, it's the average of the heights of the two sides of the trapezoid, the way we've looked at it, or you could say the average of the heights of the two parallel sides, I guess is the best way to say it. So f of 1, that's the height here, plus f of 2, all of that over 2, and then we're going to multiply it times our delta x.