📏 正弦定理计算器Law of Sines Calculator
用正弦定理 a/sin A = b/sin B = c/sin C 解三角形：支持两角一边（ASA/AAS）和两边一对角（SSA），SSA 的模糊情形会列出两个解或说明无解。Solve a triangle with the law of sines, a/sin A = b/sin B = c/sin C, for two angles and a side (ASA/AAS) or two sides and a non-included angle (SSA) — including the ambiguous case with two solutions or none.
使用说明与常见问题How-to & FAQ
「正弦定理计算器」是什么？What is the Law of Sines Calculator tool?
用正弦定理 a/sin A = b/sin B = c/sin C 解三角形：支持两角一边（ASA/AAS）和两边一对角（SSA），SSA 的模糊情形会列出两个解或说明无解。Solve a triangle with the law of sines, a/sin A = b/sin B = c/sin C, for two angles and a side (ASA/AAS) or two sides and a non-included angle (SSA) — including the ambiguous case with two solutions or none.
如何使用「正弦定理计算器」？How do I use the Law of Sines Calculator tool?
在「正弦定理计算器」中，填写「已知」、「角 A（度）」、「角 B（度）」、「边 a」、「边 b」等参数，结果会随输入实时计算并显示在下方。In the Law of Sines Calculator: Fill in "Given", "Angle A (degrees)", "Angle B (degrees)", "Side a", "Side b"; results are recalculated instantly as you type.
正弦定理是什么？What is the law of sines?
a/sin A = b/sin B = c/sin C = 2R，R 为外接圆半径。已知一组“边-对角”和另一个角或边即可解三角形。a/sin A = b/sin B = c/sin C = 2R, where R is the circumradius. Knowing one side–opposite angle pair plus one more angle or side solves the triangle.
什么是 SSA 模糊情形？What is the ambiguous SSA case?
已知两边和其中一边的对角时，sin B = b·sin A / a 可能对应一个锐角和一个钝角，于是可能有 0、1 或 2 个三角形。工具会列出所有可能的解。With two sides and a non-included angle, sin B = b·sin A / a can give an acute and an obtuse B, so there may be 0, 1 or 2 triangles. The tool lists every valid one.
计算精度如何？How precise are the results?
「正弦定理计算器」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 Law of Sines Calculator uses double-precision floating point (about 15–16 significant digits); very large or very small values may lose precision.
「正弦定理计算器」免费吗？需要注册吗？Is the Law of Sines Calculator free? Do I need an account?
「正弦定理计算器」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 Law of Sines 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.