Here is the program to find the Sinusoidal value of the given angle for the user defined accuracy. This is a fast, reliable and robust program, which uses no built in functions but a simple while loop and other math functions.

Logic: The program follows the mathematical sine series, where cosine of the entered radian angle x  is,

The program asks the user to enter the Angle x° . Also it asks for the number of iterations ‘n’ that the sine loop should iterate. As the iteration increases, the accuracy boosts up. After the desired loop, the resultant gets printed out. Similar algorithm can be set to find the Cosine value of the given number.

#include<stdio.h>
#include<math.h>
void main()
{
int i = 2, n, s = 1, x, pwr = 1, dr;
float nr = 1, x1, sum;
clrscr();
printf(“\n\n\t ENTER THE ANGLE…: “);
scanf(“%d”, &x);
x1 = 3.142 * (x / 180.0);
sum = x1;
printf(“\n\t ENTER THE NUMBER OF TERMS…: “);
scanf(“%d”, &n);
while(i <= n)
{
pwr = pwr + 2;
dr = dr * pwr * (pwr – 1);
sum = sum + (nr / dr) * s;
s = s * (-1);
nr = nr * x1 * x1;
i+= 2;
}
printf(“\n\t THE SUM OF THE SINE SERIES IS..: %0.3f”,sum);
getch();
}
Download exe and source code here.