How do you find base area?

Answer 1

Base is just the face of the figure that is usually touching the "ground," but if you are talking about a prism, it's either of the two faces of the prism that aren't the rectangles or parallelograms that make up the sides. (In a triangular prism, it's the two triangles.) To find the area, you just use the formula for the figure that makes the base. Please note that these formulas that follow might mention base, but in these formulas, they are referring to the base line of the figure--for example, the length of a rectangle. For a rectangle or square, it would be base times height. For a triangle, base times height, divided by 2. For a trapezoid, base one plus base two, divided by two, times the height. For a circle (like in a cylinder or cone), it's pi times the radius squared.

A cone and a pyramid have only one base each, but rectangular prisms have two, so you have to add both areas to get the total area of the faces.