🍕 扇形面积计算器Sector Area Calculator
由半径和圆心角（度或弧度）计算扇形面积、弧长、弦长、扇形周长和弓形面积。Sector area, arc length, chord, perimeter and segment area from radius and central angle (degrees or radians).
使用说明与常见问题How-to & FAQ
「扇形面积计算器」是什么？What is the Sector Area Calculator tool?
由半径和圆心角（度或弧度）计算扇形面积、弧长、弦长、扇形周长和弓形面积。Sector area, arc length, chord, perimeter and segment area from radius and central angle (degrees or radians).
如何使用「扇形面积计算器」？How do I use the Sector Area Calculator tool?
在「扇形面积计算器」中，填写「半径 r」、「圆心角」、「角度单位」等参数，结果会随输入实时计算并显示在下方。In the Sector Area Calculator: Fill in "Radius r", "Central angle", "Angle unit"; results are recalculated instantly as you type.
计算精度如何？How precise are the results?
「扇形面积计算器」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 Sector Area Calculator uses double-precision floating point (about 15–16 significant digits); very large or very small values may lose precision.
「扇形面积计算器」免费吗？需要注册吗？Is the Sector Area Calculator free? Do I need an account?
「扇形面积计算器」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 Sector Area 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.