The distance formula states that the distance between two points in xyz-space is the square root of the sum of the squares of the differences between corresponding coordinates. That is, given P1 = (x1,y1,z1) and P2 = (x2,y2,z2), the distance between P1 and P2 is given by d(P1,P2) = (x2 x1)2 + (y2 y1)2 + (z2 z1)2.