Quadrilateral problems on the coordinate plane

Challenge problems involving the coordinates of the vertices of the quadrilaterals.

Problem

Find the area of the parallelogram plotted below.
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3, slash, 5
  • a simplified improper fraction, like 7, slash, 4
  • a mixed number, like 1, space, 3, slash, 4
  • an exact decimal, like 0, point, 75
  • a multiple of pi, like 12, space, p, i or 2, slash, 3, space, p, i
unitsstart superscript, 2, end superscript