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Finding the Perimeter of a Shape
Perimeter is the outside edge of a 2D shape. That shape can be a rectangle, square, circle, triangle, wobbly blob or spiky lump.
To find the perimeter: Add all the sides together
The perimeter of a shape will always be a length unit, for example centimetres, kilometres, meters, millimetres.
Perimeter is the outside edge of a 2D shape. That shape can be a rectangle, square, circle, triangle, wobbly blob or spiky lump.
To find the perimeter: Add all the sides together
The perimeter of a shape will always be a length unit, for example centimetres, kilometres, meters, millimetres.
Finding the Perimeter of a Rectangle
Rectangles always have four sides. Each side in a Rectangle is of equal length to the side opposite it. This means that the top and bottom will always be the same length, and the left and right sides will always be the same length. Instead of having to add up each side, we can use a formula to find the perimeter of a rectangle. This formula uses what we already know, which is to add all the sides, as well as the fact that opposite sides will always be the same length. Instead of counting opposite sides twice, we can just multiply it by two. This way, instead of writing b + b + h + h, we can write b x 2 + h x 2. This formula will only work on a rectangle. |