C++ cmath tan-1

The C++ cmath library provides the function atan() which returns the inverse tangent (also known as arctangent) of a given value in radians.

The syntax for using atan() function is:

#include <cmath>

double atan(double x);

Here, x is the value whose inverse tangent is to be calculated.

Example:

#include <iostream>
#include <cmath>

using namespace std;

int main()
{
   double x = 1.0;
   double y = 0.5;
   
   double angle1 = atan(x);
   double angle2 = atan(y);
   
   cout << "The inverse tangent of " << x << " is " << angle1 << " radians." << endl;
   cout << "The inverse tangent of " << y << " is " << angle2 << " radians." << endl;
   
   return 0;
}

Output:

The inverse tangent of 1 is 0.785398 radians.
The inverse tangent of 0.5 is 0.463648 radians.

Note that the result returned by atan() is in radians. To convert it to degrees, you can use the radian to degree conversion formula: `angle_in_degrees = angle_in_radians * (180 / PI)` where PI is a constant value defined in cmath library.