The code draws only the wedge … circle drawn here for perspective only.

// Usage
var wedge={
    cx:150, cy:150,
    radius:100,
    startAngle:0,
    endAngle:Math.PI*.65
}

drawWedge(wedge,'skyblue','gray',4);

function drawWedge(w,fill,stroke,strokewidth){
    ctx.beginPath();
    ctx.moveTo(w.cx, w.cy);
    ctx.arc(w.cx, w.cy, w.radius, w.startAngle, w.endAngle);
    ctx.closePath();
    ctx.fillStyle=fill;
    ctx.fill();
    ctx.strokeStyle=stroke;
    ctx.lineWidth=strokewidth;
    ctx.stroke();
}