## Write a C++ program to compute Sin(x)

Hi. I'm having problem writing this program as my assignment. I've spent hours on this but still i can't get the right answer.

Here is the question:
Write a C++ program to compute Sin(x) where

x x^3 x^5 x^7 x^9 x^n
sin (x) = ----- ─ ---- + ---- ─ ---- + ----- ─ …………. ------
1! 3! 5! 7! 9! n!

Your program should accept two values from the user (the angle x and the value of n) and then should compute and print the value of sin(x).

To make the program, do following tasks.

• Write two functions, i.e. function to calculate factorial and function to calculate power having following prototypes.
double Factorial (int n); //Factorial function prototype
double Power(double x, int y); //Power function prototype
• Use these functions in your main function to compute the series.

Till now, I've written the following program but I am not able to get the right answer.

#include <iostream>
using namespace std;

double fact (int f); //declaration of factorial function

double power(double x, int y); //declaration of power function

int main()
{
int x=0; //value of x in the series
float sum_pos = 0;
float sum_neg=0;
float t_sum=0;

cout << "Enter the value of x: " << endl;
cin >> x;

for (int i=1; i<=1000; i+=4)
{
sum_pos = sum_pos + (power (x,i) / fact (i));
}

for (int i=3; i<=1000; i+=4)
{
sum_neg = sum_neg + (power (x,i) / fact (i));
}

t_sum = sum_pos - sum_neg;

cout << "Sin of " << x << " = " << t_sum << endl;

return 0;
}

//Function for Factorial
double fact (int x)
{
double f=1;

if (x==0)
{
return f;
}

else
for (int i=1; i<=x; i++)
{
f=f*i;
}

return f;
}

//Function for Power
double power (double x, int y)
{
int p=1;

for (int i=1; i<=y; i++)
p=p*x;

return p;
}