C库函数 asin() C库函数 acos() C库函数 atan() C库函数 asin() #include <stdio.h> #include <math.h> #define PI 3.14159265 int main () { double x, ret, val; x = 0.9; val = 180.0 / PI; ret = asin(x) * val; printf("The arc sine of %lf is %lf degrees", x, ret); return(0); } C库函数 acos() C库函数 atan()