Answer:
Zero
Explanation:
Given the equation of an ellipse:
[tex]\frac{x^2}{a^2}+\frac{y^2}{b^2}=1[/tex]
The eccentrity of an ellipse is given by:
[tex]e=\sqrt{1-\frac{b^2}{a^2}}[/tex]
For a circle, we have
[tex]a=b[/tex]
Therefore the eccentricity of a circle is
[tex]e=\sqrt{1-\frac{1^2}{1^2}}=0[/tex]