Results 1 to 2 of 2

Math Help - Parabola Question - Urgent

  1. #1
    Newbie
    Joined
    Jun 2007
    Posts
    22

    Unhappy Parabola Question - Urgent

    A person is building a dome shaped display cabinet with its edge modelled by the equations a(x) = -0.5x^2 + 90. Assume the base of the cabinet is the x-axis.

    If the shelves are to be built at 20 cm intervals (from the base). Find the coordinates of each end of the four shelves.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,671
    Thanks
    299
    Awards
    1
    Quote Originally Posted by mibamars View Post
    A person is building a dome shaped display cabinet with its edge modelled by the equations a(x) = -0.5x^2 + 90. Assume the base of the cabinet is the x-axis.

    If the shelves are to be built at 20 cm intervals (from the base). Find the coordinates of each end of the four shelves.
    I'll do the first one.
    The first shelf is 20 cm above the base, so a(x) = 20 where x is the coordinate of either end. (If you look at the graph of a(x) you'll see it's centered on the y-axis.) Thus we need to solve:
    20 = -0.5x^2 + 90

    0.5x^2 = 70

    x^2 = 140

    x = \pm \sqrt{140} = \pm 2 \sqrt{35}

    So the ends of the first shelf are at
    (-2 \sqrt{35}, 20) \text{ and } (2, 2 \sqrt{35})

    Can you do the other 3 shelves?

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Parabola question
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: June 8th 2010, 11:15 PM
  2. Parabola question
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: June 6th 2010, 12:45 PM
  3. urgent parabola problem plz help!
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: January 2nd 2009, 07:14 AM
  4. I need urgent urgent hel with this parabola question
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: December 14th 2008, 04:48 PM
  5. Parabola QUestion
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: January 16th 2007, 06:36 PM

Search Tags


/mathhelpforum @mathhelpforum