What is the length of foot of perpendicular drawn from the point P (3, 4,5) on Y-axis?

When we drawn perpendicular from the point P(3, 4,5) on Y-axis, the r and e-coordinates will be zero andy-coordinate will be 4. i.e., coordinate on Y-axis Q(0, 4, 0)..'. Distance between P and Q = PQ=(3−0)2+(4−4)2+(5−0)2=32+02+52=9+25=34 units