﻿ Example of C Program/Code to find the value of cos(x) using the series
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# Find the value of cos(x)

```/* Write a C program to find the value of cos(x) using the series *
* up to the given accuracy (without using user defined function) *
* Also print cos(x) using library function.                      */```

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

void main()
{
int n, x1;
float acc, term, den, x, cosx=0, cosval;

clrscr();

printf("Enter the value of x (in degrees)\n");
scanf("%f",&x);

x1 = x;

x = x*(3.142/180.0);
cosval = cos(x);

printf("Enter the accuary for the result\n");
scanf("%f", &acc);
term = 1;
cosx = term;
n = 1;

do
{
den = 2*n*(2*n-1);
term = -term * x * x / den;
cosx = cosx + term;
n = n + 1;
} while(acc <= fabs(cosval - cosx));

printf("Sum of the cosine series = %f\n", cosx);
printf("Using Library function cos(%d) = %f\n", x1,cos(x));
} /*End of main() */
/*------------------------------
Output
Enter the value of x (in degrees)
30
Enter the accuary for the result
0.000001
Sum of the cosine series = 0.865991
Using Library function cos(30) = 0.865991

RUN 2
Enter the value of x (in degrees)
45
Enter the accuary for the result
0.0001
Sum of the cosine series = 0.707031
Using Library function cos(45) = 0.707035
---------------------------------------------*/