Hey,
suppose I have got two quadratics varying with variable Q1 and two quadratics varying with Q2,
eg. P1=a+b*Q1^2 and P11=c+d*Q1^2
P2=e+f*Q2^2 and P22=g-h*Q2^2
where a,b,c,d,e,f,g and h are finite constants such that curves P1 and P11 intersect at two values of Q1, one being negative and the other positive. The same is true for curves P2 and P22. Now, I can plot curves P1 and P2 on a 3D plot (x-axis = Q1 and y-axis=Q2 and z-axis=P1=P2...