title: Check if a point is in a rotated rectangle (C#)
body: <p>I have a program in C# (Windows Forms) which draws some rectangles on a picturebox. They can be drawn at an angle too (rotated).</p>
  
  <p>I know each of the rectangles' start point (upper-left corner), their size(width+height) and their angle. Because of the rotation, the start point is not necessarely the upper-left corner, but that does not matter here.
  Then when I click the picturebox, I need to check in which rectangle (if any) I have clicked.</p>
  
  <p>So I need some way of checking if a point is in a rectangle, but I also need to take into account the rotation of each rectangle.
  Does anybody know of a way to do this in C#?</p>