How to plot a Parametric Function in the HP49
You plot parametric functions writting the function as a complex number

For example,
Plot the function:
X=2*SIN(T)
Y=COS(T)
Press 2D/3D (the key F4)
to access PLOT

Press EDIT and type the equation
In HP49 syntax one write
(2*SIN(T), COS(T))
or
2*SIN(T) + i*COS(T)
It converts automaticaly to
2*SIN(T) + i*COS(T)
if COMPLEX MODE is ON.
Press OK
Set the independent variable as T
Press ERASE DRAW

The plot is the elypsis
shown in the picture.