How to Find the Area of Basic 2-D Figures

Video Transcript

"Hi, I'm Steve Jones and we are going to look at calculating the area of 2-D; two-dimensional figures. First of all these figures can be of any kind, you can see we have some general looking shapes here, and obviously to calculate these simply is not possible. There is no simple formula for these shapes. But let's look at our basic shapes we have got the triangle. We know the area of the triangle is half the base times the height. Half bxh. We have a circled and we know pie r squared is the area of the circle. We know the rectangle is the width x the length. So, these are basic shapes we do know he area of and can calculate the area of. So now, if I start to look at the shapes here maybe you already know we are going to be able to do certain things with these shapes to make them easer to calculate. You' see why I've drawn that in a moment. But lets look at that one first. I can see here two shapes, at least to shapes. I can see here two simple shapes, if I draw a dotted line across here, I have got a triangle, and I've got a rectangle. The triangle from here that's a circle and that's a rectangle. So I know here I can apply the formula half bxh. Here. I can apply the formula of width x length. Ad the two together and I end up with the area of the shape. Now with this shape, we can actually divide it in two ways. This way creating two rectangles or this way also creating two rectangles. If we do that, we will still end up with the same area, but in two different ways. Our third shape. With our third shape, we can divide it into a triangle and again two rectangles. So we still have our basic shapes. Our final fourth shape by doing this we actually got a half circle here, half circle here, and a rectangle in the middle. So when trying to find the areas of two-dimensional figures, what we have to do is look at the figure, the divide it up using any of these three shapes. Calculate the individual areas of each one and ad them together."