Find the distance between the parallel planes x +2y-2z +1= 0 and 2x + 4y - 4z+5=0.

Explanation

We know that the distance between parallel `ax+by+cz+d_(1)=0 and ax+by+cz+d_(2)=0` is
`" "d=(|d_(1)-d_(2)|)/(sqrt(a^(2)+b^(2)+c^(2)))`
Therefore, the distance between `x+2y-2z+1=0 and x+2y-2z+(5)/(2)=0` is
`" "(|(5//2)-1|)/(sqrt(1+4+4))=(1)/(2)`