Content

• Steps
• Part 1 of 2: How to Calculate Area
• Part 2 of 2: How to Calculate Perimeter
• What do you need

A rectangle is a quadrilateral (two-dimensional shape) with four right angles. The parallel sides of the rectangle are equal. A rectangle with all sides equal is called a square. All squares are rectangles, but not all rectangles are squares. The perimeter of a figure is equal to the sum of the values ​​of its sides. The area of ​​a figure is equal to the product of its length and width.

Steps

Part 1 of 2: How to Calculate Area

1. 1 Make sure that the task is given a rectangle (shown in the figure). Remember that a rectangle has opposite sides that are parallel and equal (top and bottom sides, and sides). Moreover, the sides are perpendicular (intersecting at 90 °) to the top and bottom sides.
   • If all sides of the figure are equal, the problem is given a square. A square is a special case of a rectangle.
   • If the shape given in the problem does not meet the given conditions, it is not a rectangle.
2. 2 Write down the formula for calculating the area of ​​a rectangle:S = l x w... In this formula S - square, l - the length of the rectangle, w - the width of the rectangle. Area units are square units of length, such as square meters, square centimeters, and so on.
   • Area units are written as follows: m, cm, and so on.
3. 3 Find the length and width of the rectangle. The length of a rectangle is its top or bottom.The width of a rectangle is one of its sides. Measure the sides of the rectangle with a ruler to find the length and width.
   • For example, a rectangle is 5 cm long and 2 cm wide.
4. 4 Plug the variable values ​​into the formula and calculate the area. Plug the length and width values ​​you just found into the formula, and then multiply them to find the area of ​​the rectangle.
   • In our example: S = l x w = 5 x 2 = 10 cm.

Part 2 of 2: How to Calculate Perimeter

1. 1 Make sure that the task is given a rectangle (shown in the figure). Remember that a rectangle has opposite sides that are parallel and equal (top and bottom sides, and sides). Moreover, the sides are perpendicular (intersecting at 90 °) to the top and bottom sides.
   • If all sides of the figure are equal, the problem is given a square. A square is a special case of a rectangle.
   • If the shape given in the problem does not meet the given conditions, it is not a rectangle.
2. 2 Write down the formula for calculating the perimeter of a rectangle:P = 2 (l + w)... In this formula R - perimeter, l - the length of the rectangle, w - the width of the rectangle. Sometimes this formula is written like this: P = 2l + 2w (these formulas are identical to each other, but their form of notation is different).
   • Perimeter units are length units such as meters, centimeters, and so on.
3. 3 Find the length and width of the rectangle. The length of a rectangle is its top or bottom. The width of a rectangle is one of its sides. Measure the sides of the rectangle with a ruler to find the length and width.
   • For example, a rectangle is 5 cm long and 2 cm wide.
4. 4 Plug in the variable values ​​into the formula and calculate the perimeter. Plug in the length and width values ​​you just found into the formula. Perimeter can be calculated in two ways, depending on the formula you choose. If you chose the formula P = 2 (l + w), add the length and width values, and then multiply the sum by 2. If you chose the formula P = 2l + 2w, multiply the length by 2, then multiply the width by 2, and then add the resulting values.
   • In our example: P = 2 (l + w) = 2 (2 + 5) = 2 (7) = 14 cm.
   • In our example: P = 2l + 2w = (2 x 2) + (2 x 5) = 4 + 10 = 14 cm.

What do you need

• Paper
• Pen or pencil
• Ruler to measure sides