$($True$/$False$)$ Circle in your answer.

$($I$)$ The intersection of $x^2+z^{2}4$ and $y=1$ in $R^3$ is a circle.

True

False

$($II$)$ The equation $x+2y=6$ represents a line in $R^3.$

True

False

$($II$)$ If $u-v$ and $u+v$ are orthogonal, then $|u|=|v|.$

True

False