Topic: CYLINDERS AND CONES
Shows that the net of a cylinder is made up of two circles and a rectangle. The total surface area of the cylinder will be the total area of the two circles and the rectangle.
Then, fold the rectangle until you make an open cylinder with it. An open cylinder is a cylinder that has no bases. A good real life example of an open cylinder is a pipe used to flow water if you have seen one before
Next, using the two circles as bases for the cylinder, put one on top of the cylinder and put one beneath it.
Obviously, the two circles will have the exact same size or the same diameter as the circles obtained by folding the rectangle
You Finally, you end up with your cylinder!
Now, what did we go through so much trouble? Well if you can make the cylinder with the rectangle and the two circles, you can use them to derive the surface area of the cylinder. Does that make sense?
The area of the two circles is straightforward. The area of one circle is π × r2, so for two circles, you get 2 × π × r2
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