Surface Area of a Rectangle

Surface Area of Rectangular Prisms

Math 8

Mrs. Wimberley

Poll

I remember how to calculate the area of a rectangle.

• I sure do

• ummm..... maybe not

Multiple Choice

To calculate the surface area of a rectangle I would use which formula?

• length x width

• length + width

• add all sides

Surface Area

To calculate the surface area of a rectangle or parallelagram, we will MULTIPLE the base by the width.

Surface area of a Rectangular Prism

• Since the area of a rectangle is base times width, we can use this to find the surface area of a rectangular prism

• To do this, we will add the area of all of the rectangles together

• This is why we need to understand nets AND algebra

Calculating area with nets

We can draw a net of the 3D shape to more easily calculate the surface area. This is how the values would relate.

Example

Calculating area without a net

We can also calculate the area of a prism without a net by using a formula. The formula does all the "work" for us of adding each side together. Since rectangular prisms are created of 6 faces, and each face as an identical "pair" we only need to calculate the area of 3 sides, then multiply that by two.

Example

Open Ended

What is the area of the following prism?

Open Ended

What is the area of the following prism?

Practice Time

Please complete the practice questions/handout

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