Let P(2,−1), Q(6,3) and R(−1,4) be three points in the plane.
a. (i) Calculate the value of S=2A, where A is the (signed) area of △PQR.
b. (ii) State whether the vertices P,Q,R are ordered clockwise or anticlockwise.
c. (iii) Hence find the magnitude of the area of △PQR.