The cells in the grid each have length 1. What is the area enclosed by the geoboard quadrilateral below? Express your answer as a decimal rounded to the nearest tenth. 
+128408 We can use something known as "Pick'sTheorem" to answer this...
When the vertices of a figure have integer coordinates [ like this one]....the area is given by
(Number of integer coordinates on the boundary / 2 ) +( number of interior points with integer coordinates) - 1
Number of integer coordinates on the boundary = 5
Number of integer coordinates in the interior = 21
So....the area is
(5/2) + 21 - 1 =
2.5 + 20 =
22.5 units^2
