Question

Hi,
Can you please help me to solve the following problem.
I have the five basic parameters of the ellipse [xCenter, yCenter, Semi-Major, Semi-minor, theta].
How can I derive the ellipse coefficients [a,b,c,d,e,f] in the following quadratic equation:
a*x^2 + b*x*y + c*y^2 + d*x + e*y + f = 0

I deeply appreciate your helps.
Many Thanks