Results 1 to 4 of 4

Math Help - coordinate geometry

  1. #1
    Newbie
    Joined
    May 2009
    Posts
    1

    coordinate geometry

    1) A line with a y intercept at A(0,25) makes an angle of 30 degrees with the y axis as shown. What are the coordinates of B, the x intercept of the line?

    2) C is the center of the circle that has x intercepts at the points A and B. The radius is 6 cm. The line OC is 10cm long and joins the origin to the center and makes an angle of 35* degree
    with the x axis. CD is perpendicular bisector of AB. Calculate the length of the cord AB
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor alexmahone's Avatar
    Joined
    Oct 2008
    Posts
    1,074
    Thanks
    7
    1) I'm assuming that B lies on the positive side of the x-axis.

    tan 30=\frac{OB}{AO}
    \frac{1}{\sqrt3}=\frac{OB}{AO}
    \frac{1}{\sqrt3}=\frac{OB}{25}
    OB=\frac{25}{\sqrt3}
    So the coordinates of B are ( \frac{25}{\sqrt3}, 0).
    Last edited by alexmahone; May 27th 2009 at 04:24 AM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member
    Joined
    Jan 2009
    Posts
    591
    Quote Originally Posted by alexmahone View Post

    [snip]

    tan 30= \frac{OB}{AO}
    \sqrt3=\frac{OB}{AO}
    Could you elaborate?

    my calculator is different
    \sqrt{3}= 1.732050808...
    \tan 30 = 0.577350269
    \tan 60 = 1.732050808
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor alexmahone's Avatar
    Joined
    Oct 2008
    Posts
    1,074
    Thanks
    7
    I made a mistake
    tan 30 = \frac{1}{\sqrt3}
    Sorry.

    Edit: Fixed my previous solution.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. coordinate geometry
    Posted in the Geometry Forum
    Replies: 3
    Last Post: March 11th 2011, 06:44 AM
  2. Coordinate Geometry
    Posted in the Geometry Forum
    Replies: 3
    Last Post: March 8th 2011, 03:08 PM
  3. Coordinate Geometry
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: October 20th 2010, 01:11 AM
  4. looks like coordinate geometry but is not really...
    Posted in the Pre-Calculus Forum
    Replies: 6
    Last Post: May 19th 2009, 09:14 AM
  5. coordinate geometry
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: January 16th 2007, 08:17 PM

Search Tags


/mathhelpforum @mathhelpforum