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WBJEE · Maths · Three Dimensional Geometry

Angle between the planes \(x+y+2 z=6\) and \(2 x-y+z=9\) is

  1. A \(\frac{\pi}{4}\)
  2. B \(\frac{\pi}{6}\)
  3. C \(\frac{\pi}{3}\)
  4. D \(\frac{\pi}{2}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\frac{\pi}{3}\)

Step-by-step Solution

Detailed explanation

Equations of planes are \(x+y+2 z-6=0\) and \(\quad 2 x-y+z-9=0\) \(\cos \theta=\frac{a_{1} a_{2}+b_{1}b_{2}+c _{1}c_{2}}{\sqrt{a_{1}^{2}+b_{1}^{2}+c_{1}^{2}} \sqrt{a_{2}^{2}+b_{2}^{2}+c_{2}^{2}}}\) \(=\frac{1 \times 2+1 \times(-1)+2 \times 1}{\sqrt{1+1+4} \sqrt{4+1+1}}\)…