Surface Area of Rectangular Prisms

Unit 4, Lesson 16

Today’s standard: CCSS.MATH.CONTENT.7.G.B.6Solve real-world and mathematical problems involving area, volume and surface area of two- and three-dimensional objects composed of triangles, quadrilaterals, polygons, cubes, and right prisms.

How will you prove you understand this topic? By scoring at least 75% (3 out of 4) on the exit ticket.

Surface area is the combined area of every side of a 3-D shape.

Painting the outside of a 3-D object or wrapping it in paper would require knowing the surface area.

To calculate the surface area, find the area of each side by itself and add them together.

A rectangular prism has 6 sides so you would find the area of and then add them together.

Example

What is the surface area of this rectangular prism?

Let’s start by finding the area of the front face.

Example

Area of front:

3 cm x 5 cm = 15 cm²

The back and front are equal so the back also = 15 cm²

Next, let’s figure out the left/right sides

Example

Area of right side:

4 cm x 5 cm = 20 cm²

The left side is also 20 cm².Finally, let’s figure out the

top/bottom

Example

Area of bottom:

3 cm x 4 cm = 12 cm²

The top is also 12 cm².

Example

Surface area = 15 + 15 + 20 + 20 + 12 + 12 = 94 cm²

Surface area is units² even though it’s a 3-D shape because you are painting flat areas, not filling up the volume.

front back right left bottom

top

Find the surface area