函数 泰勒级数求sinx和cosx

Question

大佬，我这个程序运行出来是0.98，请问问题出在哪儿了呢？

/*Purpose:．设计二个子函数分别计算sinX和cosX， 要求精度为1.0e-6。在主函数中调用函数求(sin30°+ cos60°)，输出结果*/
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#define PI 3.1415926
double fun1(int);
double fun2(int);

int main(void)
{
    int x = 30, y = 60;
    double a, b;

    a = fun1(30);
    b = fun2(60);

    printf("sin30°+ cos60° = %.2lf\n", a + b);

    system("pause");
    return 0;
}
double fun1(int x)
{
    double i, y, t, fsin;
    i = 1.0;
    y = x * PI / 180.0;
    t = y;
    fsin = 0.0;

    while(fabs(t) > 1.0e-6)
    {
        fsin += t;
        i += 2.0;
        t = -y * y * t / (i * (i-1.0));
    }
    return fsin;
}
double fun2(int x)
{
    double i, y, t, fcos;
    i = 0.0;
    y = x * PI / 180.0;
    t = y;
    fcos = 1.0;

    while(fabs(t) > 1.0e-6)
    {
        i += 2.0;
        t = -y * y * t / (i * (i-1.0));
        fcos += t;
    }
    return fcos;
}

Answer 1

sin没错是0.5，cos是0.47640
斗胆改了一下你的代码

i = 0;
    y = (x / 180.0 ) *PI;
    t = y;
    fcos = 1.0;
    tl=1;
    fz=1;


   while(fabs(t) > 1.0e-6)
    {

        i=i+2;
        tl=(i-1)*i*tl;
        fz=y*y*fz*(-1);
        t = fz / (tl);
        fcos =fcos+ t;


    }