math - Java - How to check of a point is inside a sliceof a circle -

i have circle drawn, , want make can have more slices four. can 4 quadrants because check if mouse in in circle , inside box.

this how checking if point in circle.

if( math.sqrt((xx-x)*(xx-x) + (yy-y)*(yy-y)) <= radius) {     return true; } else {     return false; } 

how can modify if circle divided more 4 regions?

first can check point within circle did. woudln't combine check quadrant (is why have radius/2 ?)

if( (xx-x)*(xx-x) + (yy-y)*(yy-y) > radius*radius)    return false; 

now can see region point in using atan2 function. atan2 arctan except arctangent function returns value between -pi/2 , pi/2 (-90 , +90 degrees). need actual angle in polar coordinate fashion. assuming (x,y) center of circle , interested in location of point (xx,yy) have

  double theta = math.atan2(yy-y,xx-x);   //theta in range -math.pi math.pi   if(theta<0)      theta = math.pi - theta;   //now theta in range [0, 2*pi]   //use value determine slice of circle point resides in.   //for example:   int numslices = 8;   int whichslice = 0;   double slicesize = math.pi*2 / numslices;   double slicestart;   for(int i=1; i<=numslices; i++) {       slicestart = i*slicesize;       if(theta < slicestart) {           whichslice = i;           break;       }   }   //whichslice should number 1 8 representing part of circle   // point in, slices numbered 1 numslices starting   // right middle (positive x-axis if center (0,0).