To calculate the area of a rectangle in Excel, you need to multiply the length with height. That being said, use this formula: =<cell with length>*<cell with height>.

The surface area is made up of the end faces and rectangular faces that join them. To calculate the total surface area of a prism: Find the area of the two end faces.

A simple guide on how to show the surface area of a cone is π × radius × length, aimed at students aged 11 to 14.