rejection method in python to compute area of ellipse

I am trying to calculate the area of an ellipse by using the rejection method, where (((x^2)/25)+((y^2)/36))=1.

So after reading I know I need to have the pdf which is the area under the curve. So to calculate it I need to integrate the equation above. Therefor, y = 6 - (6x)/5

f(x) = integral of (6 -(6x)/5) dx from 0 to x.