cos curve on html Canvas

var y =125 - 120*( Math.cos(( Math.PI/180 ) * angle))

More about Math.sin() with radian or degree as input

Drawing Curves , Graphs , Grids on Canvas

var my_canvas=$('#my_canvas').get(0)
var gctx = my_canvas.getContext("2d");
/////// Axis //////
gctx.beginPath();
gctx.lineWidth=3;
gctx.shadowColor = '#ffffff';
gctx.strokeStyle= '#0060c0';
gctx.moveTo(0, 125); 
gctx.lineTo(595,125); // Horizontal X Axis 
gctx.moveTo(10, 2);
gctx.lineTo(10,248);  // Vertical Y Axis
gctx.stroke(); 
////////Axis end///
gctx.beginPath();

for (var angle = 0; angle <590; angle+=5){
var y =125 - 120*( Math.cos(( Math.PI/180 ) * angle))
var x=10 + angle;
gctx.lineTo(x,y);
}
gctx.strokeStyle= '#f00000';
gctx.stroke();