Mensuration: How the Math formula of cylinders was born

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Cylinders are long circular tubes that you see everywhere — in your science experiments, a tin can, and more.

Cally was bored in class. Their best friend was sitting far away from it. So they couldn’t play or interact.

Cally and their friend are looking at each other 

For self-entertainment, Cally created a cylindrical “telescope” using its A4 notes to “zoom in” and find out what the friend is doing.

3 steps to making a “telescope” 

Unfortunately, their form teacher, Mrs Soh, saw it and got furious. She stomped over to Cally’s desk and confiscated the “telescope”.

Cally had to hand over the “telescope” they made

As punishment, Mrs Soh made Cally calculate the outer surface area of the “telescope” (which is also in the shape of a cylinder).

Cally, being really smart, realised that the outer surface area is actually just the area of the A4 paper. That means…

Cally had a lightbulb moment

So the formula to get the curved surface area of a cylinder is:

Circumference of circle x length of cylinder (or height, depending on how you see it)

Voilà! The formula of the cylinder was born, saving the world from devastation.

*The story is 100% fictional. Only the formula is real here. In case you were wondering.

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