Question

The equation $xy=0$ in $3D$ space represents

• A. a pair of straight lines
• B. a plane
• C. a pair of planes at right angles
• D. a pair of parallel planes

Answer 1

Answer: (C)

$xy=0\Rightarrow$ either $x=0$ i.e., yz-plane or $y=0$, i.e., $xz$-xz-plane which represents a pair of planes at right angles