函数名: acos

功 能: 反余弦函数

用 法: double acos(double x);

程序例:

#include <stdio.h>

#include <math.h> int main(void)

{

double result;

double x = 0.5; result = acos(x);

printf("The arc cosine of %lf is %lf\", x, result);

return 0;

}

acos 函数值范围是 [0，π]