This C Program calculates the value of cos(x).

Here is source code of the C program to calculate the value of cos(x). The C program is successfully compiled and run on a Linux system. The program output is also shown below.

`/*`

`* 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 <math.h>`

`#include <stdlib.h>`

void main()

`{`

int n, x1;

float accuracy, term, denominator, x, cosx, cosval;

printf("Enter the value of x (in degrees) \n");

scanf("%f", &x);

x1 = x;

`/* Converting degrees to radians */`

x = x * (3.142 / 180.0);

cosval = cos(x);

printf("Enter the accuracy for the result \n");

scanf("%f", &accuracy);

term = 1;

cosx = term;

n = 1;

`do`

`{`

denominator = 2 * n * (2 * n - 1);

term = -term * x * x / denominator;

cosx = cosx + term;

n = n + 1;

} while (accuracy <= fabs(cosval - cosx));

printf("Sum of the cosine series = %f\n", cosx);

printf("Using Library function cos(%d) = %f\n", x1, cos(x));

`}`

$ cc pgm15.c -lm $ a.out Enter the value of x (in degrees) 60 Enter the accuracy for the result 0.86602 Sum of the cosine series = 0.451546 Using Library function cos(60) = 0.499882 $ a.out Enter the value of x (in degrees) 45 Enter the accuracy for the result 0.7071 Sum of the cosine series = 0.691495 Using Library function cos(45) = 0.707035

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If you wish to look at other example programs on Mathematical Functions, go to C Programming Examples on Mathematical Functions. If you wish to look at programming examples on all topics, go to C Programming Examples.