How can I calculate if a given point is wrapped inside a pentagon? If I have a pentagon and I know the coordinates of it's nodes, how do I calculate if a point is wrapped inside it?
An example to clarify what I mean: 
Assume that we know the coordinates of the points a,b,c,d,e in the pentagon below. How can I calculate if the point α is actually inside the shape?

I can calculate if a point is wrapped inside a square (nodes: a,b,c,d) by creating a boolean expression:

(α.x >= a.x AND α.x <= b.x AND α.y >= a.y AND α.y <= c.y)

Let $\alpha$ be located at $(x_\alpha,y_\alpha)$. Let $AB(x)$ be a function denoting the line connecting the points $A$ and $B$. Then we know that $\alpha$ is below the line if $AB(x_\alpha)>y_\alpha$. Use this for the other $4$ lines and see if you can create another boolean expression. 
