课后题6-2-(5) 计算sin（x）

#include <stdio.h>
#include  <math.h>
int main(void)
{
	int n = 1, count = 1;
	float x;
	double sum, term;
	printf("Input x:");
	scanf("%f", &x);
	sum = x;
	term = x;
	do{
		term = -term * x * x / ((n + 1) * (n + 2));  
                //相邻两项之间的关系，添加负号不用进行sign的变换 
		sum = sum + term;		
		n = n + 2;
		count++;	//计算次数
	}while (fabs(term) >= 1e-5);
	printf("sin(x) = %f, count = %d\n", sum, count);
	return 0;
}