14th one

Dear Student,

x = a cosθ​ 
cosθ​ = $\frac{x}{a}$   ............. (1) 
y = b sinθ 
sinθ = $\frac{y}{b}$        ................ (2)

From (1) and (2) 
cos²θ + sin²θ = $\frac{x^2}{a^2}+\frac{y^2}{b^2}$
$\frac{x^2}{a^2}+\frac{y^2}{b^2}$ = 1
This is the equation of ellipse.
Therefore, e² = $\frac{a^2-b^2}{a^2}$

Regards