W3School TIY Editor

#include <stdio.h> #include <math.h> int main() { const double PI = 3.141592653589793; printf("%f\n", cos(3)); printf("%f\n", cos(-3)); printf("%f\n", cos(0)); printf("%f\n", cos(PI)); printf("%f\n", cos(PI / 2.0)); return 0; }