Please help!

Approximate methods:

If R1 = { (x,y) | f(x,y) = 0 } and R2 = { (x,y) | g(x,y) = 0 },

then

  (R1 and R2) ~ { (x,y) | abs(f(x,y)) < d and abs(g(x,y)) < d }

or

  (R1 and R2) ~ { (x,y) | f(x,y)^2 + g(x,y)^2 < d^2 },

where d is a small positive number.