1.c=4, a=5, so b=3, and the focus is on the y axis, so the parameter equation is:

X=3cosθ, y=5sinθ, (θ is a parameter), θ ∈ [0,2π].

2.x=3tanθ, y=4secθ, (θ is the parameter).

3.x = 4t, y = 4t 2 (t is the parameter)