The angle between the pair of planes represented by the equation is

MATHEMATICS · Single correct · IB Diploma Programme · Mathematics: Analysis and Approaches · Geometry and Trigonometry · Geometry and Trigonometry

Problem

The angle between the pair of planes represented by the equation

2x^2-2y^2+4z^2+6xz+2yz+3xy=0

is (1)

\cos^{-1}\left(\frac{1}{3}\right)

(2)

\cos^{-1}\left(\frac{4}{21}\right)

(3)

\cos^{-1}\left(\frac{4}{9}\right)

(4)

\cos^{-1}\left(\frac{7}{\sqrt{84}}\right)