Expert: Richard J. Raridon - 11/14/2006

Question
I was working on ellipses, and  they were doing two distances, and a a constant multiplied by two. (PF1) + (PF2) = 2a. they got to a step where they squared it, and lost me. do you know any way that i can know what they are doing here? they want an answer in standard ellipse form. where a>b.
(this is just my algebra 2 class. i am a junior. i am homeschooled.)

Answer
the standard equation for an ellipse is
(x-h)^2/a^2 +(y-k)^2/b^2 = 1 or
(y-k)^2/a^2 +(x-h)^2/b^2 = 1 depending upon whether the major axis is parallel to the x-axis or the y-axis.
The center of the ellipse is at (h,k), the major axis is 2a and the minor axis is 2b.