Your sister is considering two different shapes of her garden. one is a square with side lengths of 3.5 meters, and the other is a circle with a diameter of 4 meters. find the area of the square.

A square always has 4 equal sides. this is a well known fact and this can be used to deduce the area of the square. We also know that the length of one side of the square is 3.5 metres. Then to finding the area of the square is easy.
Area of the square = (3.5 * 3.5) square metres
                               = 12.25 square metres
So the area of the square garden is 12.25 square metres.
the formula of calculating area changes with the shape of the garden. this formula will not work if the garden is rectangular or circular in shape.