function isPtInsidePolygon(r, a, rBnds, aBnds, vangles) {
    if(!isAngleInsideSector(a, aBnds)) return false;

    var r0, r1;

    if(rBnds[0] < rBnds[1]) {
        r0 = rBnds[0];
        r1 = rBnds[1];
    } else {
        r0 = rBnds[1];
        r1 = rBnds[0];
    }

    var polygonIn = polygonTester(makePolygon(r0, aBnds[0], aBnds[1], vangles));
    var polygonOut = polygonTester(makePolygon(r1, aBnds[0], aBnds[1], vangles));
    var xy = [r * Math.cos(a), r * Math.sin(a)];
    return polygonOut.contains(xy) && !polygonIn.contains(xy);
}
is pt (r,a) inside polygon made up vertices at angles 'vangles'
inside a given polar sector

@param {number} r : pt's radial coordinate
@param {number} a : pt's angular coordinate in *radians*
@param {2-item array} rBnds : sector's radial bounds
@param {2-item array} aBnds : sector's angular bounds *radians*
@param {array} vangles : angles of polygon vertices in *radians*
@return {boolean}