3.a line L in 3 space has vector equation X=(3,2,1)+ a(1,2,2). Find the distance
from P=(1,0,1) to line L
I tried use this this formula to solve d=(ax+by+cz-d)/sqrt root (a^2+b^2+c^2)
but its wrong
2，Two planes are perpendicular if they have perpendicular normal vectors. find a cartesian equations for a plane which passes through point P=(1,2,3) and is perpendicular to plane 2x+2y-z=1 and also to plane x+y-1=3.
3,The point A=(1,2,1,1),B=(2,3,0,3),C=(1,1,2,-1) in R4 from a triangle in R4. find a point D in R4 such ABCD is a parallelogram.