Function incircle

pub fn incircle(a: Point2, b: Point2, c: Point2, d: Point2) -> Certified

Is d inside the circle through a, b, c?

Sign::Positive means inside when a, b, c are counter-clockwise. Callers that cannot guarantee that orientation must normalise it first with orient2d, because the sign of this determinant flips with it.

Always Certified::Certain.