Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Confusion about ellipses

  1. Nov 2, 2011 #1
    This is a really dumb question, but could someone quickly explain why it is that if b > a in the equation of an ellipse then y is the major axis. Just intuitively I want to think that y^2/5 as opposed to y^2/3 is going to be smaller for a given value of y since each value is being limited by the dividend. The opposite is true. Can someone explain this simply?
     
  2. jcsd
  3. Nov 2, 2011 #2
    [itex]\frac{x^2}{a^2}+\frac{y^2}{b^2}=1[/itex]

    The distance [itex]r[/itex] of every point of the ellipses from the centre of the frame of reference is always between [itex]min(a,b)\leq r\leq max(a,b)[/itex].
    By definition, the major axis is defined as [itex]max(a,b)[/itex] while the minor axis is [itex]min(a,b)[/itex].
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook