9.
AP = (x-1)^2 + (y+2)^2 + (z-3)^2
PB = (x+3)^2 + (y-1)^2 + (z-2)^2
AP/PB = 1/sqrt(2)
I will leave you to finish it of.
10.
z^2 = x^2 + y^2 (note z>=0)
=> 2x^2 + 2y^2 = 1
=> x^2 + y^2 = 1/2 coordinates are such that (x, y) are on the point of the circumference of the circle with radius 1/sqrt(2)
If we know that x^2 +y^2 = 1/2 then this means z = sqrt(1/2) = 1 / sqrt(2)
I will leave you to finish it off.
Minor notes:
9) I just gave it a go.
10) Generally for parametric questions your making some variable the subject or performing substitution.