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Areas and perimeters

Areas and perimeters

Transcription :

Today, we are going to be talking about how to find the area and perimeter of irregular shapes.

We know how to find the area and perimeter of rectangles and squares, but how do we find the area and perimeter of a shape like this.

Well, it’s not as difficult as it might look. Let’s start with the perimeter. To get the perimeter, we do the same thing that we do for a rectangle or a square, we just add up all the sides. The difference is that instead of four sides, we have more.

Six plus four plus two plus three plus four plus seven gives us twenty-six centimeters. Don’t forget the label!

To get the area, all we need to do is divide this shape into smaller shapes whose area you can find.

For this shape, the easiest way to do it would be to divide it into two rectangles.

Now, I’ve crossed at the seven and the two because those measurements don’t apply to the two rectangles that I’ve created.

The top rectangle has a length of six and a width of four. The bottom rectangle has a length of four and a width of three.

To get the area of these two rectangles all we need to do is multiply length times width.

For the top rectangle that’s six times four is twenty-four square centimeters, and for the bottom rectangle, that will be four times three is twelve square centimeters.

But we’re not finished yet because we need to find the area of the whole shape. To do that we need to add up our two smaller rectangles, so twenty-four square centimeters plus twelve equals thirty-six square centimeters.

Sometimes, you won’t be able to divide the shape into two rectangles, you might have to divide it into three or four,

That’s ok, just get the total area for each smaller rectangle and add them all up, that’s it!

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