Surface area of cylinders examples.

OK. So.

I was totally going to blog today about our new math unit figuring out the surface area of cylinders. But, I saw that Eric already wrote about that. So, I'm just going to show some examples of figuring out the surface area of a cylinder.

Let's say that the radius is 4cm and the height is 8cm. We need to find out the surface area for the complete cylinder.

The formula is:
SA = 2(πr²) + 2πrh
Now, we solve
SA = 2π(4cm)² + 2π(4cm)(8cm)
SA = 2π(16cm²) + 2π(32cm²)
SA = 2(3.14)(16cm²) + 2(3.14)(32cm²)
SA = 100.48cm² + 200.96cm²
SA = 301.44cm²
The surface area is 301.44cm².

Now, we have an example with an open-ended cylinder. Or, you could say, just the curved part.

The radius is 3cm and the height is 7cm.
The formula is:
SA = 2πrh (<- you will notice this is just the second half of the full formula)
SA = 2π(3cm)(7cm)
SA = 2π(21cm²)
SA = 2(3.14)(21cm²)
SA = 131.88cm²
The surface area is 131.88cm².

Just a note, you probably realized that I figured out how to do a squared symbol! On the keyboard, you press and hold Alt and then type 0178. Now, you can get ²²² (I'm very proud of myself for finding that...)

So, until next week.
-K