How can a I create an array of points in C# that I can use to make an arc that I want????

i am building a picture of a node in a b tree. i have it all complete but now i want to be able to add individual colors to each data cell. it looks like the way to do this is by creating a region and then shading that region. now, shading the rectangles in the node is no problem. however shading the two cells on the end wich have semi circles as half of their border is where I am lost.





I see that I can create a region by using an array of points. I get the concept of this but I dont know how to generate the array of points for the arc that I want. ....can you help me?

How can a I create an array of points in C# that I can use to make an arc that I want????
Please post this to Computers and Internet, you can probably get a better answer there than in the math forum.