Which biconditional is a good definition?
ATwo lines are parallel if and only if they never intersect
BFour points are non-coplanar if and only if they have the same measure
DAn angle is obtuse if and only if it's measure is greater than ninety degrees
ATwo lines are parallel if and only if they never intersect
BFour points are non-coplanar if and only if they have the same measure
DAn angle is obtuse if and only if it's measure is greater than ninety degrees