# Lesson 12

What is Surface Area?

Let’s cover the surfaces of some three-dimensional objects.

### Problem 1

What is the surface area of this rectangular prism?

16 square units

32 square units

48 square units

64 square units

### Problem 2

Which description can represent the surface area of this trunk?

The number of square inches that cover the top of the trunk.

The number of square feet that cover all the outside faces of the trunk.

The number of square inches of horizontal surface inside the trunk.

The number of cubic feet that can be packed inside the trunk.

### Problem 3

Which figure has a greater surface area?

### Problem 4

A rectangular prism is 4 units high, 2 units wide, and 6 units long. What is its surface area in square units? Explain or show your reasoning.

### Problem 5

Draw an example of each of these triangles on the grid.

- A right triangle with an area of 6 square units.
- An acute triangle with an area of 6 square units.
- An obtuse triangle with an area of 6 square units.

### Problem 6

Find the area of triangle \(MOQ\) in square units. Show your reasoning.

### Problem 7

Find the area of this shape. Show your reasoning.