Area of triangle with vertices (x1, y1), (x2, y2) & (x3, y3) is given by _______.

A ½[ x1(y2+y3) - x2(y3+y1) - x3(y1+y2)]
B ½[ x1(y2-y3) + x2(y3-y1) + x3(y1-y2)]
C ½[ x1(y2-y3) - x2(y3-y1) + x3(y1-y2)]
D ½[ x1(y2-y3) + x2(y3-y1) - x3(y1-y2)]