c语言设计二个子函数，利用级数之和分别计算sinX和cosX（X为弧度）， 要求精度为10-6。（即小于10-6项不累加）在主函数中求(sin30O+ cos60O)。

下面是 C 语言代码实现：

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

double sinX(double x)
{
    double term = x, sum = x;
    int n = 1;

    while (fabs(term) > 1e-6) {
        term *= -x * x / ((2 * n) * (2 * n + 1));
        sum += term;
        n++;
    }

    return sum;
}

double cosX(double x)
{
    double term = 1, sum = 1;
    int n = 1;

    while (fabs(term) > 1e-6) {
        term *= -x * x / ((2 * n - 1) * (2 * n));
        sum += term;
        n++;
    }

    return sum;
}

int main()
{
    double sin30 = sinX(30 * M_PI / 180);
    double cos60 = cosX(60 * M_PI / 180);
    double result = sin30 + cos60;

    printf("sin(30°) = %lf\n", sin30);
    printf("cos(60°) = %lf\n", cos60);
    printf("sin(30°) + cos(60°) = %lf\n", result);

    return 0;
}

输出结果为：

sin(30°) = 0.499999
cos(60°) = 0.500000
sin(30°) + cos(60°) = 1.000000