# Eccentricity of the Ellipse

#### TonyC

How would I find the eccentricity of the ellipse:
x^2/49 + y^2/64 = 1

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#### TD

Homework Helper
The standard form of an ellipse is $$\frac{{x^2 }}{{a^2 }} + \frac{{y^2 }}{{b^2 }} = 1$$.

Another constant c is defined as: $c^2 \equiv a^2 - b^2$

Finally, we define the eccentricity as: $e = \frac{c}{a}$

#### HallsofIvy

Homework Helper
Do you know a formula for eccentricity? I would be very surprized if your textbook asks a question like this and does not include a formula!

If your textbook does not have such a formula or you do not have a textbook (not a good idea!) you could go to "google.com" and enter "ellipse eccentricity". I just did that and found a very simple formula at the first hit.

#### TonyC

Thank you very much