# 12.1: Surface Area of Cylinders

Difficulty Level: At Grade Created by: CK-12

This activity is intended to supplement Geometry, Chapter 11, Lesson 2.

## Problem 1 – Nets

Start the Cabri Jr. application by pressing the APPS key and selecting CabriJr. Open the file CYLINDER by pressing , selecting Open..., and selecting the file. You should see a partial net of a right cylinder.

1. What changes occur to the net when the point is dragged?

2. What changes occur to the net when the point is dragged?

3. Record 2 sets of measurements of the net:

Circle Radius Rectangle Height Rectangle Length

4. What is the result when you divide the Rectangle Length by the Circle Radius?

5. Explain this result. Drag point to confirm your conjecture.

## Problem 2 – Surface Area

6. Record these measurements:

Circle Area: __________

Rectangle : __________

Rectangle Area: __________

Rectangle : __________

7. Record the steps you performed to find the surface area of the cylinder:

1. _________________________________
2. _________________________________

8. What is the surface area of your cylinder?

9. How is the method used in #7 above related to the formula ?

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