Checking objects in a circle

[Deliverance]

And just in case you aren't using that class, you said:



The 'math' needed to do this is simple: You cast a ray, any direction, from the point in question (usually done to the right). If the ray / vector intersects the boundary of the circle (i.e. at some point lies on the circle) only once, then it is inside the circle. If it intersects it twice, or not at all then it is outside the circle.

Reading your math suggestions makes me want to pull out my university books again. I'm starting to get rusty. These type of solutions don't come to my mind anymore.