Can someone please explain to me the meaning of this statement in relation to calculating the volume of tetrahedron ?
"We shall often get negative value for volume of a tetrahedron. We define the volume OABC to be positive if the rotation determined by ABC is anti-clockwise with respect to O" i.e
$Vol(OABC)=-Vol(ADBC)=-Vol(ABDC)=Vol(ABCD)$
And further, if i have three given point A,B and C, then volume of PABC should be $${1\over 6}|...|$$ or $$-{1\over 6}|...|$$