How to calculate the perimeter of the rectangle

The ability to find the perimeter of the rectangle is very important to solve many geometric tasks. Below is a detailed instruction for finding the perimeter of different rectangles.

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How to find the perimeter of a conventional rectangle

The usual rectangle is a quadrangle, in which the parallel sides are equal and all angles \u003d 90º. To find its perimeter there are 2 ways:

We fold all sides.

Example:

Calculate the perimeter of the rectangle, there is its width equal to 3 cm, and the length is 6.

Solution (sequence of actions and reasoning):

Since we know the width and length of the rectangle, finding its perimeter will not be difficult. The width is parallel to the width, and the length length. Thus, in the usual rectangle 2 widths and 2 lengths.
We fold all sides (3 + 3 + 6 + 6) \u003d 18 cm.

Answer: P \u003d 18 cm.

The second way is as follows:

It is necessary to fold the width and length, and multiply by 2. The formula of this method has the following form: 2 × (a + b), where A is width, B - length.

As part of this task, we will receive such a decision:

2 × (3 + 6) \u003d 2 × 9 \u003d 18.

Answer: P \u003d 18.

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How to find a rectangle perimeter - square

Square is the right quadrangle. It is right because all of its parties and corners are equal. To find its perimeter there are also two ways:

Fold all his parties.
Multiply his side to 4.

Example: find the perimeter of the square, if its side \u003d 5 cm.

Method 1:

Solution:

Since we know the side of the square, we will be able to find its perimeter.

We fold all sides: 5 + 5 + 5 + 5 \u003d 20.

Answer: P \u003d 20 cm.

Method 2:

Multiply the side of the square on 4 (because everyone is equal): 4 × 5 \u003d 20.

Answer: P \u003d 20 cm.

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How to find a rectangle perimeter - online resources

Despite the fact that the above-mentioned actions are easy for understanding and mastering, you can use several online calculators to help you calculate the perimeters (area, volume) of different figures. Just take the necessary values \u200b\u200band the mini-program will calculate the perimeter of the figures you need. Below is a small list: