SOLUTION: we are doing these types of questions in class. i am having a problem understanding how to solve.can you help? the foci of the ellipse x^2/a^2+y^2/b^2=1b>a are_______ thanks

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: we are doing these types of questions in class. i am having a problem understanding how to solve.can you help? the foci of the ellipse x^2/a^2+y^2/b^2=1b>a are_______ thanks       Log On


   

Question 74668: we are doing these types of questions in class. i am having a problem understanding how to solve.can you help?
the foci of the ellipse x^2/a^2+y^2/b^2=1b>a are_______
thanks for any insight into this..
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
%28x%5E2+%2F+a%5E2%29+%2B+%28y%5E2+%2F+b%5E2%29+=+1 (b > a)
My math book shows this general equation in a slightly different
form, but I'm not confused by it. My book says
%28y%5E2%2Fa%5E2%29+%2B+%28x%5E2%2Fb%5E2%29=+1 (a > b)
It says that this equation is centered at the origin and the major axis
is the y-axis. It really says exactly the same thing as your
equation, with a and b reversed. Just say "The denominator associated
with the y^2 term is greater than the denominator associated with the
x^2 term."
I'm told c%5E2+=+a%5E2+-+b%5E2 and the foci are at y+=+%2Bc and y+=+-c
y+=+%2Bsqrt%28a%5E2+-+b%5E2%29 the 1st foci
y+=+-sqrt%28a%5E2+-+b%5E2%29 the 2nd foci
If b > a in your equation, the foci would be on the x-axis