See Section 13.16.1 for checking elements in two-dimensional geometry.
The is_element command determines whether or not a geometric object is contained in another.
Examples.
| P:= plane([0,0,0],[1,2,-3],[1,1,-2]) |
| is_element(point(2,3,-5),P) |
| 1 |
| L:= line([2,3,-2],[-1,-1,-1]); |
| P:= plane([-1,-1,-1],[1,2,-3],[1,1,-2]); |
| is_element(L,P) |
| 0 |