⬡ 正多边形计算器Regular Polygon Calculator
输入正多边形的边数和边长、外接圆半径、内切圆半径（边心距）或面积中的任意一个，求出面积、周长、内角、外角、对角线数量等。Enter the number of sides and any one of the side length, circumradius, inradius (apothem) or area of a regular polygon to get its area, perimeter, interior and exterior angles, diagonals and more.
使用说明与常见问题How-to & FAQ
「正多边形计算器」是什么？What is the Regular Polygon Calculator tool?
输入正多边形的边数和边长、外接圆半径、内切圆半径（边心距）或面积中的任意一个，求出面积、周长、内角、外角、对角线数量等。Enter the number of sides and any one of the side length, circumradius, inradius (apothem) or area of a regular polygon to get its area, perimeter, interior and exterior angles, diagonals and more.
如何使用「正多边形计算器」？How do I use the Regular Polygon Calculator tool?
在「正多边形计算器」中，填写「边数 n」、「已知量」、「数值」等参数，结果会随输入实时计算并显示在下方。In the Regular Polygon Calculator: Fill in "Number of sides n", "Known value", "Value"; results are recalculated instantly as you type.
正多边形面积公式？Regular polygon area formula?
面积 = ½ × 周长 × 边心距 = n·s² ÷ (4·tan(π/n))，其中 n 为边数、s 为边长。Area = ½ × perimeter × apothem = n·s² ÷ (4·tan(π/n)), with n sides of length s.
内角怎么算？How are the angles found?
每个内角 = (n − 2) × 180° ÷ n，外角 = 360° ÷ n，内角和 = (n − 2) × 180°；对角线条数 = n(n − 3)/2。Each interior angle = (n − 2) × 180° ÷ n, exterior = 360° ÷ n, the interior sum = (n − 2) × 180°, and there are n(n − 3)/2 diagonals.
计算精度如何？How precise are the results?
「正多边形计算器」使用 JavaScript 双精度浮点数（约 15–16 位有效数字）；极大或极小的数值可能存在精度误差。The Regular Polygon Calculator uses double-precision floating point (about 15–16 significant digits); very large or very small values may lose precision.
「正多边形计算器」免费吗？需要注册吗？Is the Regular Polygon Calculator free? Do I need an account?
「正多边形计算器」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Regular Polygon Calculator is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.