Find the parametric equations of the following circles :

$x^2+y^2+2x-4y-1=0$

$x=5\cos \theta ,y=5\sin \theta$

$x=a+c\cos \alpha , y=b+c\sin \alpha$

$x=3\cos \alpha , y=3\sin \alpha$

$x=1+3\cos \theta , y=2-3\sin \theta$

$x=\cos \theta +\sin \theta , y=\sin \theta -\cos \theta$

$x=\frac{20t}{4+t^2}, y=\frac{5\left(4-t^2\right)}{4+t^2}$