1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution what is the difference between the form z - zo = fx(x-xo) + fy(y-yo) and: Fx(xo,yo,zo) + Fy(xo,yo,zo) + Fz(xo,yo,zo)=0 ____________________________________________________________________________ using the first eq : while the latter gives: Am I doing something wrong? shouldn't they give the same answer?