**Example 2 revisited**

Of course, if there is not thesis, we can think of T:=0=0,

so all we have to do is elimination from ideal H, as in example 2:

Elim(r..l, Ideal(A^2-((r-l)^2+s^2), B^2-(r^2+ s^2), C^2-l^2, ls-2S))

Ideal( A^4 - 2A^2B^2 + B^4 - 2A^2C^2 - 2B^2C^2 + C^4 + 16S^2 );