# tan C Library Function

The function double tan(double x); returns the tangent of x, expressed in radians.

### Function prototype of tan

double tan(double x);
• x : A floating point value representing an angle in radians.

### Return value of tan

It returns the tangent of x.

### C program using tan function

The following program shows the use of tan function to calculate tangent of a radian.

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

#define PI 3.14159265

int main(){
printf("Enter an angle in degree\n");
scanf("%lf", &degree);

/*
*  One degree is equal to PI/180 radians.
*  Where PI = 22/7 = 3.14159(approx)
*/

printf("The tangent of %lf is %lf\n", degree, value);
return 0;
}

Output

Enter an angle in degree
45
The tangent of 45.000000 is 1.000000

Enter an angle in degree
60
The tangent of 60.000000 is 1.732051