Visual C++ :: MFC Coordinate System - Drawing Of Angles?

I am drawing in a simple (square) MFC window. I realize that (0,0) starts in the upper left hand corner. I wanted to see how MFC handled drawing of angles, so I use this code:

Code:
double CompassDegreesToRadians(double compassDegrees) {
return((PI / 2.0f) - (compassDegrees * PI / 180.0f));
}
// Make pen
CPen penRed;
penRed.CreatePen(PS_SOLID | PS_COSMETIC, 1, RGB(255, 0, 0));
// Test Angles

[Code] .....

Using this code, and changing the value of angle1 to these values (0, 90, 180, 270) I think MFC uses the coordinate system:

Code:
180 -y
|
|
-x 270---------------- 90 +x
|
|
0 +y

This seems like a strange coordinate system to use. Am I doing something wrong? If this is correct, how can I convert my calculations to this coordinate system? (compass degrees):

Code:
0 +y
|
|
-x 270---------------- 90 +x
|
|
180 -y