Question

Distance between two parallel planes 2x+y+2z=8 and 4x+2y+4z+5=0 is

• A. $\frac{9}{2}$
• B. $\frac{5}{2}$
• C. $\frac{7}{2}$
• D. $\frac{3}{2}$

Answer 1

The correct option is C $\frac{7}{2}$

Given planes are 2x+y+2z-8=0
or 4x+2y+4z-16=0 $\cdots \left(i\right)$
and 4x+2y+4z+5=0 $\cdots \left(ii\right)$
Distance between two parallel planes
$=\left|\frac{-16-5}{\sqrt{4^2+2^2+4^2}}\right|=\frac{21}{6}=\frac{7}{2}$