Question
Find the distance from P (2, 1, – 1 ) to the plane x – 2 y + 4 z = 9.
Solution
The equation of plane is x – 2y + 4z - 9 = 0.
Let p be the length of perpendicular from P (2, 1, – 1) to the plane.

Let p be the length of perpendicular from P (2, 1, – 1) to the plane.
