Question
In each of the following cases, determine the direction cosines of the normal to the plane and the distance from the origin.
x + y + z = 1
Solution
The equation of plane is x + y + z = 1
Dividing both sides by
It is of form lx + my + nz = p
where
∴ direction cosines of the normal to the plane are
and distance from origin 
Dividing both sides by
It is of form lx + my + nz = p
where
∴ direction cosines of the normal to the plane are
and distance from origin 
