# Stereographic projection in R^4

whattttt
I am computing a stereographic projection in R^4 and i think i am correct in setting
x=rcos(x)sin(y)
y=rsin(x)sin(y)
z=rcos(y)
but can't see how to compute r as I do not know to visualise it graphically as was possible in R^3, any help would be greatly appreciated

Tinyboss
That doesn't look like stereographic projection to me...do you mean spherical?

whattttt
No. In a previous example it was in R^3 and polar coordinates were used with x=rcosx and y=rsinx and r was computed from the diagram and equaled something like 2tan(pi-theta) which could be computed from the diagram by projection onto the x-axis but I'm not sure if such a formula exists in R^4