Sunday, March 21, 2010

Finding a diameter, circumference, radius of a circle.

The picture above is the radius and the diameter of a circle.

This is what we worked on in Math on March 19. 2010.

Find the diameter of a circle with a radius of 12.6 m.
Show the formula you need and all the work.
  • d = 2r
  • d = 2 ( 12.6 )
  • d = 25. 2 m
Find the radius of a circle when the diameter is 10.5 cm.
Show the formula and work. Remember, when finding
the radius of a circle, make sure you divide it by two.
  • r = d / 2
  • r = 10.5 / 2
  • r = 5.25 cm
Find the circumference of a circle with a diameter of 3 mm.
Show formula and work.
  • c = π d
  • c = 3.14 ( 3 )
  • c = 9.42 mm
Find the circumference of a circle with a radius of 5m.
Show formula and work.
  • c = 2 π r
  • c = 2 (314 ) ( 5 )
  • c = 10 ( 3.14 )
  • c = 31.4 m
When finding a circumference, you have to divide it by π.
When finding a diameter, you have to multiply the number by 2.
And when finding the radius, you divide it by two. Hope this helps. (:
Please alert me if I get an answer wrong. Thanks. :)


  1. And I hope you understand there is no video to show you. ):

  2. Great post Maya! You talked about some of the things we learned so far and even told us the formulas. I liked the pictures you used and your post was easy to understand. Keep up the good work:)

  3. Loved how the answers got darker and darker. It was really fun! You could put up a quick definition of a radius and the diameter, but other than that it was great.
    It was also how you commented on your own blog post explaining why you didn't have a video!
    Go check out my blog post at:

  4. Great job, Maya! You had nice pictures, definitions, and such. You included basically everything we learned that day. Good post!

  5. good job maya!next time look for a video or sumthing.

  6. Good Job Maya! You explained everything that we did that day very neatly and the pictures were good too. Good job again!!

  7. Good job. You explained everything well. Next time you could have put a link. Other than that you did good.

  8. Great post Maya. Your post was very understandable. But you should have put a link to somthing about pi or something related to a circle. Other than that, Great job! :)

  9. Great job Maya! Your post was easy to understand and it had all the things we worked on that day. You had two good pictures, maybe next time try to find a link. Other than that good job.(:

  10. Maya, I really like the fact that everything was easy to follow and it was appealing to me. But next time, I suggest you put a link and a video. I really enjoyed your post! Great job!

  11. Great post Maya! I like how your pictures are big, and your blog is very understandable and organized. Keep it up!

  12. Good Job Maya. I liked your pictures. Your post is really easy to understand . Excellent Job ! :]

  13. wow what a big picture. any ways good job maya you did a awesome job and good job on the colours!

  14. really good job maya i loved ur pic and u talked about the key things we are learning about area

  15. Good post Maya(: You explained everything well and your pictures were good. One thing you could have done was maybe make the font bigger. And maybe get a link.