Question

Sally is calculating the perimeters of a number of rectangles, such as the one shown here. She uses the formula P = 2l + 2w. Her younger brother Joe comes by and suggests simplifying the formula to P = 4w. Sally corrects Joe's algebra, but he tries his formula on a rectangle and gets the correct answer! (She checks his work.) What can Sally conclude from this?

Answer 1

The rectangle has equal sides on all four sides which means the shape is a square since a square can be considered a rectangle.