Function G2(StartX, StartY, EndX, EndY, Radius)

I stared at this a dozen times this weekend and it dawned
on me this morning what the problem was. I'm humbled

Thanks Ross C and Stevie G for your help and my brother for
remembering the slope algorithm

Graphics 640, 480, 32, 2
SetBuffer BackBuffer()
x1#=320
y1#=240
r#=100
While Not KeyHit(1)

	x2# = MouseX()
	y2# = MouseY()
	r# = Abs(MouseZ()*3)+rf#
	q# = Sqr( ((x1 - x2)*(x1 -x2)) + ((y1 - y2)*(y1 - y2)))

	rf#=q#*.5

	x3#=(x1+x2)/2
	y3#=(y1+y2)/2
		
	x# = x3 + Sqr(r^2-(q/2)^2)*(y1-y2)/q
	y# = y3 + Sqr(r^2-(q/2)^2)*(x2-x1)/q  

	angleToStart#=NAngle(ATan2(y1#-y#,x1#-x#)) 
	angleToEnd#=NAngle(ATan2(y2#-y#,x2#-x#))
	
	LockBuffer()
	
	If angleToEnd>angletoStart
		For angle# = angleToStart To angleToEnd Step 0.05  
			WritePixel x + Cos( angle ) * r , y + Sin( angle ) * r , $FFFFFF
			plotpath=1
		Next
	Else
		For angle# = angleToStart To 360 Step 0.05 
			WritePixel x + Cos( angle ) * r , y + Sin( angle ) * r , $FFFFFF
			plotpath=0
		Next
		For angle# = 0 To angleToEnd Step 0.05 
			WritePixel x + Cos( angle ) * r , y + Sin( angle ) * r , $FFFFFF
			plotpath=0
		Next
	EndIf	
	
	UnlockBuffer()
	Oval(x-2,y-2,4,4)
	Text 10,0,plotpath
	Text 10,10,x+" "+ y +" radius: " + r
	Text 10,20,x1 + " " + y1+"  Start Angle: "+angletostart
	Text 10,30,x2+" "+y2+" End Angle: "+angletoend
	

	Flip 0
	Cls
Wend

Function NAngle#(angle#)
	If angle#<0 Then angle#=180+(180+angle#)
	Return angle#
End Function