The distance of point I(3, 4,5) from the yz-plane is

When we draw a perpendicular line from P(3,4, 5) on the yz-plane the r-coordinate will be zero and the othercoordinate y and e will be 4 and 5, i,.e. coordinate on yz-plane be Q(0, 4,5). Distance between P and Q = PQ=(3−0)2+(4−4)2+(5−5)2=32+02+02=3 units