函数名: cos 功能: 余弦函数 用法: #include <math.h> double cos(double x); 程序例: #include <stdio.h> #include <math.h> int main(void) { double result; double x = 0.5; result = cos(x); printf("The cosine of %lf is %lf\n", x, result); return 0; } ...