Consider the points P(3,7), Q(−2,4) and R(5,−1) taken in the order P,Q,R. What is the sign of the determinant 3−2574−1111 and hence the orientation of the triangle?
(a) Positive; vertices are clockwise
(b) Zero; vertices are collinear
(c) Positive; vertices are counter-clockwise
(d) Negative; vertices are clockwise