console 命令行工具 X clear

console

//var result=CircleCenter(1190,630,1170,610,20);
var result=CircleCenter(970,530,950,510,20);
//var result=CircleCenter(0,0,20,20,20);
console.log(result);
var x=result[0];
var y=result[1];
console.log(x);
console.log(y);
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
ctx.arc(x, y, 20,0,Math.PI/2,false);
ctx.strokeStyle = "blue";
ctx.stroke();


function CircleCenter(x1,y1,x2,y2,R)  
{  
    var c1 = (x2*x2 - x1*x1 + y2*y2 - y1*y1) / (2 *(x2 - x1));  
    var c2 = (y2 - y1) / (x2 - x1);  
    var A = (c2*c2 + 1);  
    var B = (2 * x1*c2 - 2 * c1*c2 - 2 * y1);  
    var C = x1*x1 - 2 * x1*c1 + c1*c1 + y1*y1 - R*R;  
    y = (-B + Math.sqrt(B*B - 4 * A*C)) / (2 * A);
    x = c1 - c2 * y;     
    return [x,y];
}

<html>
<canvas id="myCanvas" width="4000px" height="3000px" style="border: 1px solid red;">
您的浏览器不支持canvas标签。
</canvas
</html>