Results 1 to 9 of 9

Math Help - Geometry Problems

  1. #1
    Newbie
    Joined
    Mar 2012
    From
    Somewhere...
    Posts
    6

    Geometry Problems

    6. Circle A has a radius of 10 units and Circle B has a radius of 5 units. The center of Circle B is on the circumference of Circle A. What is the difference between the area which is within A but not B and the area which is within B but not A. Put your answer as a multiple of Pi.

    30. Marna baked a batch of brownies in a 9x12 pan. She then decided to created a giant ice cream sandwich by cutting two congruent circular brownies out of the pan and placing a wedge of chocolate chip ice cream between them. What is the radius of the largest circular brownies she can cut? Express you answer as a common fraction in simplest radical form

    Please Help
    Last edited by MathStudent1999; March 18th 2012 at 04:42 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,094
    Thanks
    67

    Re: Geometry Problems

    We can only help if you show your work, else we don't know where you're stuck.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Mar 2012
    From
    Somewhere...
    Posts
    6

    Re: Geometry Problems

    I don't know how to start. These questions are just to hard for me.


    edit:
    I just got (15√2 - 15 / 2) for #30. Can someone verify this for me?
    Last edited by MathStudent1999; March 18th 2012 at 05:12 PM. Reason: Got Question 30
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,094
    Thanks
    67

    Re: Geometry Problems

    Quote Originally Posted by MathStudent1999 View Post
    I just got (15√2 - 15 / 2) for #30. Can someone verify this for me?
    You're making me nervous! That comes out to ~3.1066 ; how did you get that?
    By the way, your bracketing is not correct; should be: (15√2 - 15) / 2

    I get (21 - SQRT(216) / 2 = ~3.1515 ; quite close to yours...

    If we make the rectangle's sides a and b, then:
    maximum radius of 2 inscribed circles = [a + b - SQRT(2ab)] / 2
    Last edited by Wilmer; March 18th 2012 at 09:42 PM.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Mar 2012
    From
    Somewhere...
    Posts
    6

    Re: Geometry Problems

    Quote Originally Posted by Wilmer View Post
    You're making me nervous! That comes out to ~3.1066 ; how did you get that?
    By the way, your bracketing is not correct; should be: (15√2 - 15) / 2

    I get (21 - SQRT(216) / 2 = ~3.1515 ; quite close to yours...

    If we make the rectangle's sides a and b, then:
    maximum radius of 2 inscribed circles = [a + b - SQRT(2ab)] / 2
    Is [a + b - SQRT(2ab)] / 2 a formula?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,094
    Thanks
    67

    Re: Geometry Problems

    Quote Originally Posted by MathStudent1999 View Post
    Is [a + b - SQRT(2ab)] / 2 a formula?
    Call it whatever you want: it's the solution to your problem.
    If it hasn't been used before (which I doubt), then I'm sure I'll get no Nobel prize!

    Get some graph paper and try it using a 16 by 18 rectangle:
    you'll get an exact 5 as radius of circles, which you'll be able
    ti "fit in" perfectly; each circle is tangent to 2 sides,
    plus the circles are tangent to each other...
    Last edited by Wilmer; March 19th 2012 at 06:12 PM.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Newbie
    Joined
    Mar 2012
    From
    Sacramento,California
    Posts
    8

    Re: Geometry Problems

    Okay but I probably got this wrong,I didn't look at the other answers or replies people gave because I want to figure this out too!!

    Okay so, Circle A has a radius of 10 units and Circle B has a radius of 5 units. (That means A is bigger then B right?)

    The center of Circle B is on the circumference of Circle A. What is the difference between the area which is within A but not B and the area which is within B but not A.
    (That means it would be 5 units in difference)

    Put your answer as a multiple of Pi. I don't know how to put it in pi! So can anyone tell me? I'm super stuck too.

    Marna baked a batch of brownies in a 9x12 pan. She then decided to created a giant ice cream sandwich by cutting two congruent circular brownies out of the pan and placing a wedge of chocolate chip ice cream between them. What is the radius of the largest circular brownies she can cut? Express you answer as a common fraction in simplest radical form

    I don't get how this is possible either cause there are two congruent circle shaped brownies but it never tells you the radius of those brownies! D:
    Follow Math Help Forum on Facebook and Google+

  8. #8
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,094
    Thanks
    67

    Re: Geometry Problems

    Alice, sorry, but you're making no sense...
    the question is to calculate the radius; so radius sure won't be a given!
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Don
    Don is offline
    Newbie Don's Avatar
    Joined
    Jul 2011
    Posts
    18

    Re: Geometry Problems

    Perhaps the intersecting area can be treated as an ellipse, then the minor axis is 5 units. Major axis ??
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. geometry problems help
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: October 28th 2009, 02:58 AM
  2. geometry help problems
    Posted in the Geometry Forum
    Replies: 1
    Last Post: October 27th 2009, 09:53 AM
  3. Modern Geometry: Taxicab Geometry Problems
    Posted in the Differential Geometry Forum
    Replies: 0
    Last Post: March 30th 2009, 07:32 PM
  4. Geometry Problems
    Posted in the Geometry Forum
    Replies: 4
    Last Post: August 6th 2008, 10:07 AM
  5. few geometry problems
    Posted in the Geometry Forum
    Replies: 5
    Last Post: January 18th 2007, 06:21 AM

Search Tags


/mathhelpforum @mathhelpforum