raphael.js

function toVector(a,p,r) {
    return [p[0] + Math.cos(a)*r,p[1] + Math.sin(a)*r];
}

function opposite(a) {
    return a>0?a-Math.PI:a+Math.PI;
}

function connectTwo(a1,p1,a2,p2) {
    var a2o = opposite(a2);
    var p1h = toVector(a1,p1,50);
    var p2h = toVector(a2o,p2,50);
    console.log([a2o,p1h,p2h]);
}

connectTwo(Math.PI/2,[0,0],0,[100,100]);
connectTwo(0,[100,100],-Math.PI/4,[200,0]);

function connectPoints(a,b,c) {

}


$(document).ready(function(){

    var paper = Raphael('canvas', 400, 400);
    var c = paper.path("M0 0C0 50 50 100 100 100 150 100 164 35 200 0");
    c.attr('stroke-width',3);

});