how to shift the slider image knot outside - iphone

Question

i have difficulties understanding the math behind on how to calculate the circumference of the knots to the center of the circle. i hope you guys can give me some pointer.
the current calculation set the knot img in the middle of pie, will like to shift it nearer to the outer circle like in img 2
thank you for viewing and commenting, any comments are appreciated.
how i wan to it to be.
/** Draw a white knob over the circle **/
-(void) drawTheHandle:(CGContextRef)ctx{
CGContextSaveGState(ctx);
NSLog(#"handleCenterA.x %f",handleCenterA.x);
NSLog(#" handleCenterA.y %f", handleCenterA.y);
[[UIColor colorWithWhite:1.0 alpha:1.0]set];
UIImage *myImage = [UIImage imageNamed:#"clock-marker.png"];
//this will give me the result of image 1
[myImage drawInRect:CGRectMake(handleCenterA.x-35, handleCenterA.y-40, TB_BUTTON_WIDTH, TB_BUTTON_WIDTH)];
//this will give me the result of image 2
[myImage drawInRect:CGRectMake(handleCenterA.x-35, handleCenterA.y-40, TB_BUTTON_WIDTH, TB_BUTTON_WIDTH)];
CGContextRestoreGState(ctx);
}
#pragma mark - Math -
/** Move the Handle **/
-(void)movehandle:(CGPoint)lastPoint{
//Get the center
CGPoint centerPoint = CGPointMake(self.frame.size.width/2, self.frame.size.height/2);
//Calculate the direction from a center point and a arbitrary position.
//float currentAngle = AngleFromNorth(centerPoint, lastPoint, NO);
//int angleInt = floor(currentAngle);
//Calculate the direction from the center point to an arbitrary position.
float currentAngle = AngleFromNorth(centerPoint, lastPoint, NO);
int angleInt = 360 - floor(currentAngle);
if (sliderLock == SliderLockedStart) {
self.startAngle = angleInt;
}
//Redraw
[self setNeedsDisplay];
}
- (CGPoint)centerPointFromAngel:(int)angleInt {
CGPoint point = [self pointFromAngle:angleInt];
point.x += TB_BUTTON_WIDTH/2;
point.y += TB_BUTTON_WIDTH/2;
return point;
}
- (CGFloat)distanceBetween:(CGPoint)p1 and:(CGPoint)p2 {
CGFloat xDist = (p2.x - p1.x);
CGFloat yDist = (p2.y - p1.y);
return sqrt((xDist * xDist) + (yDist * yDist));
}
/** Given the angle, get the point position on circumference **/
-(CGPoint)pointFromAngle:(int)angleInt{
//Circle center
CGPoint centerPoint = CGPointMake(self.frame.size.width/2 - (TB_BUTTON_WIDTH/2), self.frame.size.height/2 - (TB_BUTTON_WIDTH/2));
//The point position on the circumference
CGPoint result;
result.y = round(centerPoint.y + radius * sin(ToRad(-angleInt))) ;
result.x = round(centerPoint.x + radius * cos(ToRad(-angleInt)));
return result;
}
//Sourcecode from Apple example clockControl
//Calculate the direction in degrees from a center point to an arbitrary position.
static inline float AngleFromNorth(CGPoint p1, CGPoint p2, BOOL flipped) {
CGPoint v = CGPointMake(p2.x-p1.x,p2.y-p1.y);
float vmag = sqrt(SQR(v.x) + SQR(v.y)), result = 0;
v.x /= vmag;
v.y /= vmag;
double radians = atan2(v.y,v.x);
result = ToDeg(radians);
return (result >=0 ? result : result + 360.0);
}

Answer 1

finally solved it.
/** Given the angle, get the point position on circumference **/
-(CGPoint)pointFromAngle:(int)angleInt{
//Circle center//TB_BUTTON_WIDTH
CGPoint centerPoint = CGPointMake(self.frame.size.width/2 - (TB_BUTTON_WIDTH/2), self.frame.size.height/2 - (TB_BUTTON_WIDTH/2));
//The point position on the circumference radius
CGPoint result;
result.y = round(centerPoint.y + 120 * sin(ToRad(-angleInt))) ;
result.x = round(centerPoint.x + 120 * cos(ToRad(-angleInt)));
NSLog(#"centerPoint %#",NSStringFromCGPoint(centerPoint));
NSLog(#"result %#",NSStringFromCGPoint(result));
return result;
}