Given equation of plane is 2x−y+2z−1=0....(i) ∴ DR's of normal to the given plane is (2,−1,2) Given plane meet the z-axis. Put x=0,y=0 in Eq. (i), we get 2(0)−0+2z−1=0 ⇒z=
1
2
So, the point on z-axis is (0,0,
1
2
). ∴ Angle between normal to the plane and z -axis,