The distance of the point (3, –2, 1) from the plane 2x – y + 2z + 3 = 0 is :
Answer & explanation
Correct answer: option 2
Distance of point (x, y, z) from plane Ax + By + Cz = D is
$|\frac{Ax_1 + By_1 + Cz_1 = D}{\sqrt{A^2+B^2}}|$ ....(i)
given points is (3, -2, 1)
x1 = 3, y1 = -2, z1 = 1 & equation of plane is 2x - y + 2z + 3 = 0
2x - y + 2z = -3
-(2x - y + 2z) = 3 ⇒ -2x+ y - 2z = 3
comparing with Ax + By + Cz = D
A = -2, B = 1, C = -2, D = 3
Distance of point form the plane = $|\frac{(-2×3)+(1×-2)+(-2×1)-3}{\sqrt{(-2)^2+(1)^2+(2)^2}}|$
$=|\frac{(-6)+(-2)+(-2)-3}{\sqrt{4+1+4}}|⇒|\frac{-13}{\sqrt{9}}|$
$=|\frac{-13}{3}|=\frac{13}{3}$
Option 2 is correct.