#include <stdio.h>
#include <math.h>

double funcos(double e, double x);

int main()
{
    double e, x;

    scanf("%lf %lf", &e, &x);
    printf("cos(%.2f) = %.6f\n", x, funcos(e, x));

    system("pause");
    return 0;
}

/* 你的代码将被嵌在这里 */
double funcos(double e, double x) {
    double item = 1.0, cosx = 1.0, fenzi = 1.0, fenmu = 1.0;
    int flag = -1;
    for (int i = 2; fabs(item) >= e; i += 2) {  //fabs(),求出函数的绝对值
        fenmu *= (i * (i - 1));
        fenzi *= (x * x);
        item = 1.0 * flag * fenzi / fenmu;
        cosx += item;
        flag *= -1;
    }
    return cosx;
}

fenmu *= (i * (i - 1));
fenzi *= (x * x);
item = 1.0 * flag * fenzi / fenmu;
重点！！！