Question

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

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

Answer 1

Answer: (C)

Given planes are
$4x+2y+4z+5=0$ ....(1)
$4x+2y+4z-16=0$ ....(2)
$\left[d=\frac{|c_1-c_2|}{\sqrt{16+4+116}}\right]\Rightarrow d=\left|\frac{5+16}{\sqrt{16+4+16}}\right|$
$=\frac{21}{6}=\frac{7}{2}$