# SIN Function in C

The C sin Function is a C Math Library Function used to calculate the Trigonometry Sine value for the specified expression. The syntax of the C SIN function is

`double sin(double number);`

The SIN function will return a value between -1 and 1. Before we get into the syntax of a SIN function in C, Let us see the mathematical formula behind this Trigonometry Sine:

sin(x) = Length of the Opposite Side / Length of the Hypotenuse

## SIN Function in C Example

The sin function in the math library allows you to calculate the trigonometric Sine for the specified values. This program asks the user to enter his/her own value, and then it will find the sine value of the user-specified value.

TIP: Please refer to the C ASIN Function article to calculate the Arc Sine of a specified expression.

```#include <stdio.h>
#include <math.h>

int main()
{
double sinValue, number;
printf(" Please Enter the Value to calculate Sine :  ");
scanf("%lf", &number);

sinValue = sin(number);

printf("\n The Sine value of %lf = %f ", number, sinValue);

return 0;
}```

## C SINE Function Example 2

This C Programming example allows the user to enter the value in degrees, and then we convert the degrees to Radians. And finally, we are finding the sine value of the radian.

```#include <stdio.h>
#include <math.h>

#define PI 3.14159
int main()
{
printf(" Please Enter an Angle in degrees :  ");
scanf("%lf", &degreeVal);

// Convert Degree Value to Radian
`````` Please Enter an Angle in degrees :  30