Results 1 to 7 of 7

Math Help - Calculating Distance between 2 circles

  1. #1
    Junior Member
    Joined
    Jun 2011
    Posts
    41

    Calculating Distance between 2 circles

    Calculating Distance between 2 circles-gmat-conveyer-belt.jpgThe answer right below the question is the answer, but I am unsure as to why we are dividing the entire problem by 2
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Dec 2009
    Posts
    3,120
    Thanks
    1

    Re: Calculating Distance between 2 circles

    Quote Originally Posted by KingNathan View Post
    Click image for larger version. 

Name:	gmat conveyer belt.jpg 
Views:	20 
Size:	11.8 KB 
ID:	21690The answer right below the question is the answer, but I am unsure as to why we are dividing the entire problem by 2
    It's because the conveyor belt goes all the way around.
    The conveyor belt length is the distance between the centres twice,
    and a semicircle twice.
    Hence the distance between the centres is half of "15 feet minus 2 semicircle lengths".
    The diameters of the circles is 1 foot, so their radii is 1/2 a foot.
    Finish up by calculating the length of the round part of the belt.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Jun 2011
    Posts
    41

    Re: Calculating Distance between 2 circles

    Quote Originally Posted by Archie Meade View Post
    It's because the conveyor belt goes all the way around.
    The conveyor belt length is the distance between the centres twice,
    and a semicircle twice.
    Hence the distance between the centres is half of "15 feet minus 2 semicircle lengths".
    The diameters of the circles is 1 foot, so their radii is 1/2 a foot.
    Finish up by calculating the length of the round part of the belt.
    That completely makes sense for me in cutting the entire distance of the belt in half. But then that would leave me with half of the figure left, correct?

    Calculating Distance between 2 circles-gmat-conveyer-belt-2.jpg

    At this point, how do I wind up with pie in the numerator of the final answer?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Dec 2009
    Posts
    3,120
    Thanks
    1

    Re: Calculating Distance between 2 circles

    That's another way to arrive at the answer.
    You now only need to subtract the circumferences of 2 quarter-circles.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Jun 2011
    Posts
    41

    Re: Calculating Distance between 2 circles

    Quote Originally Posted by Archie Meade View Post
    That's another way to arrive at the answer.
    You now only need to subtract the circumferences of 2 quarter-circles.
    Since the formula for the circumference of a circle of 2 pie r, then in assuming that pie r is the circumference of a semi circle (2 identical quarter circles added together), what happens to the r in the formula?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor
    Joined
    Dec 2009
    Posts
    3,120
    Thanks
    1

    Re: Calculating Distance between 2 circles

    The diameter is 1, so the radius "r" is 1/2.
    Just place r=1/2 into the formula.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Junior Member
    Joined
    Jun 2011
    Posts
    41

    Re: Calculating Distance between 2 circles

    Quote Originally Posted by Archie Meade View Post
    The diameter is 1, so the radius "r" is 1/2.
    Just place r=1/2 into the formula.
    Perfect! Thanks again for all of your help, man.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 7
    Last Post: June 7th 2012, 05:04 AM
  2. Replies: 0
    Last Post: December 9th 2011, 07:16 AM
  3. Replies: 9
    Last Post: February 1st 2011, 02:23 AM
  4. Calculating distance road
    Posted in the Geometry Forum
    Replies: 3
    Last Post: April 21st 2009, 11:31 PM
  5. Replies: 1
    Last Post: February 21st 2007, 09:18 AM

Search Tags


/mathhelpforum @mathhelpforum