How to find the area of a shape

Just as the perimeter of a shape is like a fence, the area of a shape is like tiles. You need to find out many square tiles would fit in the shape since the unit is cm2 or m2. Once you know the formula for the area of a shape, you can apply it to find the area with any numbers!

Rectangle

A rectangle has 4 sides with 2 being longer than the other 2. We call these sides the length and the shorter sides the width. To find the number of square tiles (area) that would fit inside the rectangle, we can multiply the width by the height.

Area = height x width

square

A square has 4 sides that are the same length. In order to know how many tiles the square is, you multiply the length by the width. But since the length and width is the same, it’s the same as squaring the length.

Area = side²

triangle

Imagine a rectangle that is cut in half from one corner to the opposite corner, you get 2 rectangles. Therefore, a triangle is half the area of a rectangle.

Area = 1/2 x base x height

parallelogram

It will be helpful again to imagine a rectangle first. Then, if you add a triangle on one side, and add the same triangle but upside down on the other side. So, a parallelogram is made up of a rectangle and 2 triangles. If you move the one triangle to the other side, it forms a rectangle. So, the area of a parallelogram will be the same as for a rectangle. However, it’s called the base and not the “length” and also height not “width”, like with a triangle.

Area = base x height

Rhombus

A rhombus is like a parallelogram but all 4 sides are the same length. If you divide a rhombus into 4 by cutting it diagonally from the corners, you form 4 triangles. If you rearrange these triangles, it forms a rectangle. But this rectangle, is half the height of rhombus on the diagram.