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# Cos Function

計算一個角度的餘弦值，角度以弧度為單位定義，結果在 -1 到 1 之間。

Using the angle Alpha, the Cos function calculates the ratio of the length of the side that is adjacent to the angle, divided by the length of the hypotenuse in a right-angled triangle.

Cos(Alpha) = Adjacent/Hypotenuse

### Syntax:

    Cos (Number As Double) As Double

### Return value:

Double

### Parameters:

Number：數值型表示式，用於指定要計算餘弦值的角度 (以弧度為單位)。

若要將度轉換成弧度，可將度乘以 pi/180；若要將弧度轉換成度，則將弧度乘以 180/pi。

度 = (弧度*180) /pi

弧度 = (度*pi)/180

Pi is here the fixed circle constant with the rounded value 3.14159...

### 錯誤代碼：

5 無效的程序呼叫

### Example:

    REM 以下示例以直角三角形為例，要求輸入
    REM 依據鄰邊和角度 (以度為單位)，並計算三角形斜邊的長度：
    Sub ExampleCosinus
    REM 捨入後的 PI = 3.14159
    Dim d1 As Double, dAngle As Double
        d1 = InputBox$ (""Enter the length of the adjacent side:","Adjacent")
        dAngle = InputBox("Enter the angle Alpha (in degrees):","Alpha")
        Print "The length of the hypotenuse is"; (d1 / cos (dAngle * Pi / 180))
    End Sub

相關主題

Atn Function

Sin Function

Tan Function