Tuesday, September 28, 2010


In today's math class, we worked on calculating the area of prisms and cylinders. We also worked a bit on finding the volume of a prism.

To calculate the area of faces on a cylinder, you must use the formulas:
πr² (pi x radius squared) AND 2πrh (2 x pi x radius x height)

For finding the area of the top face of a cylinder you must use the formula:

For example:
The radius of the cylinder is 5cm

π r ²(pi x radius squared)

(3.14) (5²) I got 3.14 from pi, and 5 because that is the radius.

(3.14) (25) After squaring 5, you are left with 25.

After multiplying 3.14 and 25, the top face of a cylinder would be:

You also need to know the formula for finding the area of the rectangle in a cylinder. The formula for that is:
2πrh (2 x pi x radius x height)

For example:
A cylinder has a radius of 4, and a height of 3.

2 π r h (2 x pi x radius x height)

2x(3.14) (4) (3) 3.14 represents pi, 4 is the radius, and 3 was the height

(6.28) (4) (3) I got 6.28 after multiplying 3.14 by 2

(25.12) (3) 25.12 was from multiplying 6.28 by 4

75.36cm² is the area of the rectangular face on a cylinder

For finding the surface area of a prism, you will need the following formula:
2(lxw)+ 2(lxh)+ 2(hxw)
(You add the two because there are 3 pairs of opposite sides with the same area)

For example:
A prism has a length of 5, a height of 2, and a width of 3, what is the surface area?

To start off, you would need the formula:
2(lxw)+ 2(lxh)+ 2(hxw)

Then replace the variables with their numbers:
2(5x3)+ 2(5x2)+ 2(2x3)

One at a time you multiply the brackets:
2(15)+ 2(10)+ 2(6)

Once you've done that, you multiply the lengths by 2:

Then you find your answer!

Now that were done.. just kidding we have to learn volume now.

To find the volume of a prism, you must use the formula:
WxDxH (width x depth x height)
(though they might not always give you the exact numbers)

For example:
A prism has a width of 2, a depth of 2, and a height of 2.

Start of with your fancy formula:

Fill in the numbers:

8cm³(volume is always cubed)

Thank you for reading my scribe post which took 5 hours.

WANT MORE PRACTICE? VISIT THESE SITES www.shodor.org/interactive/activities/surfaceareaandvolume www.mathguide.com/lessons/SurfaceArea.html


I choose JERIC for the next scribe.. just kidding it's actually


  1. Hello there fellow classmate. Your blog contains a lot of useful information to use in education today. It must of been a very hard job to create a blog post like this! The images are clear and very understandable. You've explained very clear on how to find the surface areas of a cylinder and rectangular prism. You have chosen colors that make it look like a rainbow, it brings out the most important parts in your post! Their seems to be nothing wrong with your post. Excellent job Emmanuel. Lots of effort has been put into this blog post.

    - Darnell ;)

  2. I really have nothing to say. Great job Emmanuel! :)

  3. Hello fellow peer . I would like to thank you for the wonderful blog post and terrific information . Your pictures were outstandable and your explanations were just strictly beautiful . You were very clear with the formulas to find Surface Area and you added examples which i thought were fantastic. You seem to know and understand Surface Area quite well and i would like to thank you for passing on your knowledge to other brains. I love your color choices and how you put brackets what the formulas ment and stood for . This post is just beautifully made , thank you for the time and effort you put in this . Way to go Emmanuel !

  4. Great job Emmanuel! I like how you explained everything clearly and gave examples. I also liked the way you suggested the websites from todays' class and encouraged people to play on Tutpup. I didn't find any errors, so good job again and keep up the outstanding work!

  5. Great job Emmanuel! I liked the way you made key words stand out. Your pictures were very nice and easy to understand. The formula was easy to understand. It was good that you added examples, maybe it was just me, but the way you had a lot of brackets, for the cylinder, made it a little confusing. But the way you explained the Surface Area of a Prism, was really understandable. Also, for the Volume of a Prism, it would've been better if you had a picture to go along with it. But other than good job!!

  6. nice job emmanuel! i liked how you put in pictures and made it neat and easy to understand, i also liked how you explained it very well. and how you made the important things a different color. good job!

  7. Good job emmanuel! Your post was very descriptive and I like how you made certain words stick out using colours. I also like how neat the pictures were. Your post was very simple yet informative. Good Job!

  8. Awesome job Emmanuel! But when you said "You also need to know the formula for finding the area of the rectangle in a cylinder", well 2 π r h isn't the formula for finding the area of a rectangle. But instead, the formula for area of rectangle is lxw. You could've explained that 2 π r is to finding the circumference of the circle. Because when you draw out a net for a cylinder, the middle part is actually a rectangle. So the circumference of the circle will kinda work as a length. While the height of the cylinder are the width. You gets? Okay so great job again. And keep it up!

  9. You explained everything clearly. I like the way you put up the sites and ...great job

  10. thanks my fellow peers. i love you all

  11. Nicely done Emmanuel! Your blog was full of information and the pictures were nicely chosen. Your explanation was very clear and easy to understand. I also liked how you used colors and changed the size of the font to point out the important information. Everything was well put together! Great job!

  12. Good job Eman. I liked how you gave us those websites to help us practice. I also like how you used lots of colors and explained things clearly. I also like your humor; it makes math seem a lot more fun.

  13. NICELY DONE! Your blog was already nice just by going through it. But when i started reading your information, looking at your posted pictures(diagrams), it was even more better. Things were clearly stated, which made is easy to understand. And the way you showed your pictures to show what your information meant made things even more easy to understand. Your use of font and colour i can say was very well done in terms of highlighting the important things and making them stand out. I also like the end part with the sites.

  14. Good job eman! I liked how you found the pi sign, and also some sites that could help us practice more. Nice to know that it took you 5 hours to do the scribe.. must of put alot of work into it? I liked the use of colours to make the important things stand out, but I think you should have put the examples in a colour too, because it seems complicted with all the numbers and words. Good job !

  15. Good Job Emmanuel! This post had really helped me a little since you explain the formula step by step! The colors you used to make certain things stand out was pretty good too! And the sites that you gave was also helpful too to improve my knowledge! In other words awesome job!

  16. Wow really long comments people, good job Eman, nice use of font to make the important parts noticeable. Good job explaining all the formulas and the steps to get to the answers, and good job remembering the websites. Nice job!