 So far we found how to develop equations 1 and 2. Now let's look how we get number 3 and number 4. For number 3 we start with again, the changing position is the area, all the blue area here, under the curve. But this time we split it up. We look at our area in one rectangular shape and one triangle B. So if you look at it, A over here, rectangular shape plus the triangle. So now the rectangular shape is pretty easy. It's V initial times delta T. If you look here, delta T times V initial. So that's easy to calculate. The other one is you have V initial down there and V final up here. This is exactly half of a square with delta T on one side and delta V, which is V initial to be final on the other side. If you look at it over here, delta V over here and the big square here. It's exactly half of it. For we have one half delta V delta T. You also know that acceleration is a slope. Therefore delta V over delta T is acceleration or delta V is the acceleration times delta T. We simply multiply both sides with delta T. Now if we combine those two here we get delta S is delta V initial. Sorry delta V initial times delta T. V initials times delta T plus one half times delta V, which is A delta T, times delta T, which gives one half A delta T square. Which is our third equation. Now if you look at our fourth equation, it looks kind of similar. Also it is. This time we're starting with the big red square. Which is the area right here. Which is nothing else than V final times delta T. So we find delta T and then we subtract the white triangle here. That white triangle, which is exactly the same area as the blue triangle. Namely one half times velocity, changing velocity times delta T. Which is what we already calculated, one half A delta T square. Therefore we get delta S is the big red square. V final times delta T minus one half A delta T square. You see the difference in number three. We took that small square down here A and we added B to find the complete area. In number four we start with the big red square or shape. And we subtract the white triangle.