What is eccentricity of the ellipse given by the equation x^2/49 + y^2/81 =1? .63 or .81

Question

anonymous · Answer

http://www.wolframalpha.com/input/?i=+What+is+eccentricity+of+the+ellipse+given+by+the+equation+x%5E2%2F49+%2B+y%5E2%2F81+%3D1

amistre64 · Answer

isnt e = c/a?

anonymous · Answer

yes it is but im still confused...

amistre64 · Answer

well, the major axis is the larger value; and c is the focal length

anonymous · Answer

sqrt(1-49/81)

amistre64 · Answer

|dw:1335367303950:dw|
they tend to be situated like this

amistre64 · Answer

the equation gives us a and b; we would need to find c

anonymous · Answer

You don't need c if you have a and b

anonymous · Answer

sqrt(1-49/81) = 0.6285

amistre64 · Answer

doesnt c = sqrt(a^2-b^2) ?

anonymous · Answer

thank you

anonymous · Answer

Yes, it is same thing just rearranged....

anonymous · Answer

e= sqrt(1-b^2/a^2)  a>b

amistre64 · Answer

then finding c is just a part of the overall process.  you still need to find "c"  :)

sqrt(a^2-b^2)/sqrt(a^2) .... simplifies to your results.  yes