我如何在 javascript 中使用 Math.sin() 来获得正确答案？
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How do i use Math.sin() in javascript to get correct answer?
提问by JaSamSale
When I use Math.sin(90) for calculating Sine of 90 degrees in javascript it returns 0.8939966636005565, but sin(90) is 1. Is there a way to fix that? I need accurate values for any angle.
当我使用 Math.sin(90) 在 javascript 中计算 90 度的正弦时，它返回 0.8939966636005565，但 sin(90) 是 1。有没有办法解决这个问题？我需要任何角度的准确值。
<!DOCTYPE html>
<html>
<body>
<p id="demo">Click the button calculate value of 90 degrees.</p>
<button onclick="myFunction()">Try it</button>
<script>
function myFunction(){
document.getElementById("demo").innerHTML=Math.sin(90);
}
</script>
回答by thefourtheye
Math.sinexpects the input to be in radian, but you are expecting the result of 90 degree. Convert it to radian, like this
Math.sin期望输入为弧度，但您期望结果为 90 度。把它转换成弧度，像这样
console.log(Math.sin(90 * Math.PI / 180.0));
# 1
As per the wikipedia's Radian to Degree conversion formula,
根据维基百科的弧度到度数转换公式，
Angle in Radian = Angle in Degree * Math.PI / 180
回答by sjf
The sin function in Javascript takes radians, not degrees. You need to convert 90 to radians to get the correct answer:
Javascript 中的 sin 函数采用弧度，而不是度数。您需要将 90 转换为弧度以获得正确答案：
Math.sin(90 * (Math.PI / 180))
