C++ programming homework. Drawing a half circle between two straight lines.

I need to draw a half circle between two straight lines. First i need to input +X,+Y coordinates for point A, B and C. Straight lines are AC and BC. Then I need to input a radius for my half circle. After all that the half circle needs to be positioned between the 2 lines so that the point of the half circle touches points on the lines that are equally distanced from the center of the half circle. This needs to be done in C++ and I am a rookie. Thank you.