Tests if the [x,y] point is inside a closed arc.
var arc={
cx:150, cy:150,
innerRadius:75, outerRadius:100,
startAngle:0, endAngle:Math.PI
}
function isPointInArc(x,y,arc){
var dx=x-arc.cx;
var dy=y-arc.cy;
var dxy=dx*dx+dy*dy;
var rrOuter=arc.outerRadiu...