Perimeter Formula Method

Perimeter - How it Works - Video

Example 1a

Example 1a:

We need to find the perimeter of the figure. The first method is to add each individual side, 2 + 4 + 2 + 4 = 12 cm. If we take a look at the picture we rearranged the numbers to 2 + 2 + 4 + 4 then 4 + 4 + 4 then 8 + 4 then 12 cm. Either way will work. Now let's take a look at using the formula.

Example 1b

Example 1b:

We are going to use the formula for rectangles to find the perimeter. The formula is Perimeter = 2 x length + 2 x width.

Now we substitute the length and width into the equation. Usually the longer one is the length and the smaller one, the width.

Now we have 2 x 4 + 2 x 2 then 8 + 2 x 2 then 8 + 4 then 12 cm. So we have the same answer as Example 1a and you get to choose which method you prefer.

Not mentioned in the photo or video is that we can add the length and width then multiply by 2. So we 4 + 2 = 6 and next 6 x 2 = 12 cm. Once again a different way of doing the same problem.

Example 2a

Example 2a:

We need to find the perimeter of the figure. The first method is to add each individual side, 5+ 2 + 5 + 2 = 14 cm. If we take a look at the picture we rearranged the numbers to 2 + 2 + 5 + 5 then 4 + 5 + 5 then 9 + 5 then 14 cm. Either way will work. Now let's take a look at using the formula.

Example 2b

Example 2b:

We are going to use the formula for rectangles to find the perimeter. The formula is Perimeter = 2 x length + 2 x width.

Now we substitute the length and width into the equation. Usually the longer one is the length and the smaller one, the width.

Now we have 2 x 5+ 2 x 2 then 10 + 2 x 2 then 10 + 4 then 14 cm. So we have the same answer as Example 2a and you get to choose which method you prefer.

Not mentioned in the photo or video is that we can add the length and width then multiply by 2. So we 5 + 2 = 7 and next 7 x 2 = 14 cm. Once again a different way of doing the same problem.

Example 3

Example 3:

We are going to use the formula for rectangles to find the perimeter. The formula is Perimeter = 2 x length + 2 x width.

Now we substitute the length and width into the equation. Usually the longer one is the length and the smaller one, the width.

Now we have 2 x 7 + 2 x 3 then 14 + 2 x 2 then 14 + 6 then 20 cm.

Not mentioned in the photo or video is that we can add the length and width then multiply by 2. So we 7 + 3 = 10 and next 10 x 2 = 20 cm. Once again a different way of doing the same problem.

Example 4

Example 4:

We are going to use the formula for rectangles to find the perimeter. The formula is Perimeter = 2 x length + 2 x width.

Now we substitute the length and width into the equation. Usually the longer one is the length and the smaller one, the width.

Now we have 2 x 8 + 2 x 4 then 16 + 2 x 2 then 16 + 8 then 24 cm.

Not mentioned in the photo or video is that we can add the length and width then multiply by 2. So we 8 + 4 = 14 and next 14 x 2 = 28 cm. Once again a different way of doing the same problem.

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