Pick's Theorem

Pick's Theorem

Area of a polygon = Sum of Interior points + 0.5 (Sum of Edge points including the vertices) - 1

In the applet below, you can move the vertices of the triangle to change its shape and see how Pick's Theorem is applied to calculate the area.

Proof

Step 1: Show that when 2 triangles areas are added together, Pick's Theorem still holds.

Step 2: Prove for the area of a rectangle with coordinates (0, 0), (a, 0), (a, b) and (0, b) where a and b are integers.

Step 3: Prove for any triangle with vertices on lattice points.