7th Grade Math

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Surface Area

PART A B C DEF

Multi-Part

Lesson 2

Addresses

GLE 0706.1.8.

588 Volume and Surface Area

Main Idea

Find the surface area

of a cylinder.

Surface Area of Cylinders

Step 1 Trace the top and bottom of the can on grid paper. Then cut

out the shapes.

Step 2 Cut a long rectangle from the grid paper.

The width of the rectangle should be the

same as the height of the can. Wrap the

rectangle around the can. Cut off the

excess paper so that the edges just meet.

1. Make a net of the cylinder.


2. Name the shapes in the net.


3. How is the length of the rectangle related to the circles?

You can put two circles and a rectangle together to make a cylinder.

The rectangle

makes up the

curved surface.

Two congruent

circles... h C =^2 πr^ h

... make up the
two bases.

C = 2 πr

r

r

In the diagram above, the length of the rectangle is the same as the

circumference of the circle, 2πr. Also, the width of the rectangle is the

same as the height of the cylinder.

Surface Area of a Cylinder

Words The surface area S.A. of a

cylinder with height h and

radius r is the sum of the area

of the curved surface and the

areas of the circular bases.

Model

h

r

Symbols S.A. = 2 πrh + 2 πr^2

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