In this lesson you will learn about some 3-dimensional simple shapes and know how to calculate their surface area.

**Rectangular prism**

The first shape is rectangular prism or cube. The best example of cube is a box. Another example is a room. Surface area of a room is useful for painting the room.

Each cube has three dimensions; width, length and height, say W, L and H. Surface area of a cube consists of six rectangles or three pairs of rectangles. In each pair there are two identical rectangles. One pair with dimensions W and L. The second pair with dimensions W and H and the last pair with dimensions L and H.

**Rectangular Prism **

Surface area of a rectangular prism or cube is:

A = 2 (WL+WH+LH)

*Example:*

Surface area of a rectangular prism with dimensions 2, 3 and 5 meters is:

A = 2 (2×3 + 2×5 + 3×5) = 42 m^{2}

**Cylinder**

The surface area of a cylinder consists of surfaces of 2 circles and one rectangle. See the following figure.

Cylinder

The surface area of a cylinder with radius r and height h is:

A = 2πr^{2} + 2π rh

*Example:*

Find surface area of a cylinder with radius 4 and height 6 inches.

A = 2πr^{2 }+ 2π rh = 2π (4)^{2} + 2π×4 × 6 ≈ 251.2 in^{2}