C庫函數(shù)double cos(double x) 返回一個弧度角x的余弦值。
以下是cos()函數(shù)的聲明。
double cos(double x)
x -- 這是浮點值同比弧度表示的角度。
這個函數(shù)返回x的余弦。
下面的例子顯示了cos()函數(shù)的用法。
#include <stdio.h> #include <math.h> #define PI 3.14159265 int main () { double x, ret, val; x = 60.0; val = 180.0 / PI; ret = cos( x*val ); printf("The cosine of %lf is %lf degrees ", x, ret); x = 90.0; val = 180.0 / PI; ret = cos( x*val ); printf("The cosine of %lf is %lf degrees ", x, ret); return(0); }
讓我們編譯和運行上面的程序,這將產(chǎn)生以下結(jié)果:
The cosine of 60.000000 is 0.664171 degrees The cosine of 90.000000 is -0.299510 degrees