Results 1 to 3 of 3

Math Help - [SOLVED] Radius, Area And Circumference- Help!

  1. #1
    Jangalian
    Guest

    Question [SOLVED] Radius, Area And Circumference- Help!

    If a circle has a radius of 8.6 cm., find it's area and circumference.

    I'm clueless about radius and pi and everything in between...
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by Jangalian View Post
    If a circle has a radius of 8.6 cm., find it's area and circumference.

    I'm clueless about radius and pi and everything in between...
    A = pi r^2.
    C = 2pi r.

    Sub r = 8.6 cm.

    Since you're self-confessed clueless, my advice is to get a clue - these two formulae should be known to you (hopefully they are now, anyway).
    Last edited by mr fantastic; January 14th 2008 at 03:11 PM. Reason: Forgot a New Year resolution - softened the last line of this post
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Jan 2008
    Posts
    5
    Area = pi*r^2
    Circumference = pi*d
    d is the diameter, which is equal to twice the radius, as such C = 2pi*r is also an acceptable formula for the circumference of a circle.

    I assume that you've already got the answers since Mr. Fantastic gave you the formulas, so if you want to make sure you've done it correctly:

    A = pi*r^2
    A = (3.14)*(8.6)^2
    A = (3.14)*(73.96)
    A = 232.2344 cm^2

    C = 2pi*r
    C = 2(3.14)(8.6)
    C = 6.28(8.6)
    C = 54.008 cm

    Any more Questions don't hesitate to ask
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. radius given a point on circumference
    Posted in the Geometry Forum
    Replies: 4
    Last Post: September 1st 2010, 04:12 PM
  2. Replies: 12
    Last Post: November 22nd 2009, 04:02 PM
  3. Replies: 3
    Last Post: September 5th 2009, 06:13 PM
  4. Replies: 1
    Last Post: April 20th 2009, 03:26 AM
  5. Replies: 2
    Last Post: April 11th 2008, 02:03 AM

/mathhelpforum @mathhelpforum