🪁 筝形（菱形风筝）面积计算器Area of a Kite Calculator
筝形（两边对称的四边形）面积 = d₁d₂/2，其中 d₁、d₂ 是两条对角线。对角线须大于 0。本地处理。Kite area = d₁d₂/2 from the two diagonals (which are perpendicular). Diagonals must be greater than 0. Processed locally.
使用说明与常见问题How-to & FAQ
「筝形（菱形风筝）面积计算器」是什么？What is the Area of a Kite Calculator tool?
筝形（两边对称的四边形）面积 = d₁d₂/2，其中 d₁、d₂ 是两条对角线。对角线须大于 0。本地处理。Kite area = d₁d₂/2 from the two diagonals (which are perpendicular). Diagonals must be greater than 0. Processed locally.
如何使用「筝形（菱形风筝）面积计算器」？How do I use the Area of a Kite Calculator tool?
在「筝形（菱形风筝）面积计算器」中，填写「对角线 1」、「对角线 2」等参数，结果会随输入实时计算并显示在下方。In the Area of a Kite Calculator: Fill in "Diagonal 1", "Diagonal 2"; results are recalculated instantly as you type.
菱形也可以吗？Does this work for a rhombus?
可以。菱形是筝形的特例，同样用对角线：面积 = d₁d₂/2。Yes. A rhombus is a special kite, so the same formula area = d₁d₂/2 applies.
只有边长怎么办？What if I only have the side lengths?
本页用对角线。若只有边长和夹角，可用 (1/2)ab sin C 算相邻两边构成的两个三角形再相加。This page uses diagonals. With two sides and the included angle you can use (1/2)ab sin C on each pair of equal sides and add.
能举个计算实例吗？Can you show a worked example?
例如在「筝形（菱形风筝）面积计算器」中填 对角线 1 = 8，对角线 2 = 6，结果区显示：面积：24For example, entering Diagonal 1 = 8, Diagonal 2 = 6 in the Area of a Kite Calculator gives: Area: 24
哪些输入会被检查？Which inputs are validated?
「筝形（菱形风筝）面积计算器」会检查这些输入——「对角线 1」：必须填写，须大于 0且不大于 1,000,000,000,000,000；「对角线 2」：必须填写，须大于 0且不大于 1,000,000,000,000,000；绝对值超过 10¹⁵ 的数也会被拒绝。不符合时结果区显示具体提示，不会给出数字。The Area of a Kite Calculator checks its inputs — "Diagonal 1": required, must be more than 0 and at most 1,000,000,000,000,000; "Diagonal 2": required, must be more than 0 and at most 1,000,000,000,000,000; numbers above 10¹⁵ in absolute value are rejected too. When a value fails, the result area names the problem instead of showing a number.
有哪些选项可以调整？What options can I adjust?
「筝形（菱形风筝）面积计算器」的设置：「对角线 1」默认 8；「对角线 2」默认 6。每次生成结果都按当前设置处理。Settings in the Area of a Kite Calculator — "Diagonal 1" default 8; "Diagonal 2" default 6. The result always uses the current settings.
计算精度如何？How precise are the results?
「筝形（菱形风筝）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 Area of a Kite Calculator uses double-precision floating point (about 15–16 significant digits); very large or very small values may lose precision.
「筝形（菱形风筝）面积计算器」免费吗？需要注册吗？Is the Area of a Kite Calculator free? Do I need an account?
「筝形（菱形风筝）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 Area of a Kite 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.