3d triangle in one equation without min or max How can I graph a triangle in 3d with a single equation that does not use min, max, floor, ceil, or absolute value?
If you believe not possible, then the closest approximation (equation that roughly appears to be a 3d triangle) will do.

Consider the example of triangle with vertices $(0,0,0)$,$(3,3,0)$ and $(-3,3,0)$
$$((x+y) (x-y)(y-3)(\sqrt{9-x^2- (y-3)^2}+1))^2+z^2=0$$
$a^2+b^2=0$ ensures that $a=0$ and $b=0$. Here $z=0$ denotes equation of plane of triangle. $x+y=0$,$x-y=0$ and $y=3$ are 3 planes that contain 3 lines of triangle. The square root is included to exclude points on the line not a part of triangle.
