Short way:
Make sure you plot the points, list them
in a column , going counter-clockwise starting with any point.
5 7
-6 7
-5 -2
6 2
5 7 , notice I repeated the first point I listed.
area = (1/2)(sum of downwards diagonals - sum of upwards diagonals)
= (1/2)(35 + 12 -10 + 42 - (-42 - 35 - 12 + 10)
= (1/2)(79 + 79)
= 79
www.wolframalpha.com/input/?i=area+%7B%285%2C7%29%2C+%28-6%2C+7%29%2C+%28-5%2C+-2%29%2C+%286%2C+2%29%7D
Determine the area of the quadrilateral of vertices A (5,7);: B (-5, -2): C (-6, 7) and D (6, 2)
2 answers
draw a picture on graph paper
use the grid to find the area by drawing an "enclosing" quadrilateral
... and then subtracting out the right triangles
... that are not in the original quadrilateral
use the grid to find the area by drawing an "enclosing" quadrilateral
... and then subtracting out the right triangles
... that are not in the original quadrilateral
3 answers