Question

If a (-5,7), b(-4,-5), c (-1,-6) and d(4,5) are the vertices of a quadrilateral find the areas of the quadrilateral

Answer 1

area of triangle ABC=  1/2[(-5)(-5+6) + (-4)(-6-7) +(-1)(7+5) ]
= 1/2 ( -5 +52 -12)
= 35/2

and
area of triangle ACD = 1/2[(-5)(-6-5)+ (-1)(5-7)+(4)(7+6)]
= 1/2 (55+ 2 + 52)
=109/2

therefore area of quad. ABCD = area of triangle ABC​ + area of triangle ACD = 35/2 + 109/2 = 144/2 = 72 sq.unit