Video narration
What formula do you use for a rectangle? Picture a rectangular sheet of paper or tabletop. Its length and width reveal two things: the space inside and the distance around its edge. The space inside is the area. Multiply length by width: A equals length times width. A five-by-three rectangle has fifteen square units. The distance around the edge is the perimeter. Add all four sides. Because opposite sides match, double the sum of length and width: P equals two times the quantity length plus width. Perimeter uses regular length units, not square units. So, there isn't one rectangle formula. For tabletop surface, use area: length times width. For the distance around its edge, use perimeter: add length and width, then double the result.