So let's set up our trapezoids. So the first trapezoid is going to look like that. Actually, it's going to be a triangle, not really a trapezoid. Then the second trapezoid is going to look like this. I guess you could say a trapezoid where one of the sides has length zero turns into a triangle. Then the third trapezoid is going to look like this. And then the fourth trapezoid is going to look like that.