# Area of 2-dimensional convex hull of 4 points?

Let $P_1, P_2, P_3, P_4$ be four 2-dimensional points (in $\mathbb{R}^2$, that is), with coordinates $x_i,y_i$. Is there a formula for the area of their convex-hull?

• I think first you have to find the ordering of vertices on the convex hull boundary, and then you can apply the shoelace formula. – Rahul Sep 7 '16 at 14:21
• @Rahul How can I compute the ordering? – becko Sep 7 '16 at 14:33
• There are lots of convex hull algorithms, the simplest ones being gift wrapping and Graham scan. – Rahul Sep 7 '16 at 15:12