In previous grades, you learned that the volume of an object is the number of cubic units in the interior of a three-dimensional figure.

For the rectangular prism shown, there are five layers of 12 cubes each. This prism has a width of 4 units, length of 3 units, and height of 5 units. Counting the cubes reveals that the rectangular prism has a volume of 60 cubic units.

In this lesson, you will investigate other ways to calculate the volume of rectangular prisms and triangular prisms. You will use volume formulas to solve problems involving volume of prisms.

To begin this lesson, watch the video below that compares the area of a two-dimensional figure with the volume of a related three-dimensional figure. The video also compares the volume of triangular prisms to the volume of rectangular prisms.

Based on what you saw in the video, answer the following questions:

• What are the area formulas for rectangles and triangles?

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  Check Your Answer

  Area of a Rectangle: A = bh or A = lw
  Area of a Triangle: A = 1 over 2 1 2 lw or A = lw ÷ 2

• What is the volume formula for a rectangular prism?

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  Check Your Answer

  Volume of a Rectangular Prism: V = lwh or V = Bh