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Sheza Naveed

The ** atan() function** returns the inverse tangent of a number. Figure 1 shows the C++ representation of the mathematical expression.

To use the `atan()`

function, the `cmath`

header file needs to be included in the program, as shown below:

```
#include <cmath>
```

It takes a single number as an argument that can be positive, negative, or zero. This value can be a `float`

, `double`

or `long double`

.

It returns a single value of an angle in radians, ranging from ‘-π/2’ to ‘π/2’. This value can be a `float`

, `double`

, or `long double`

:

```
double atan(double x);
float atan(float x);
long double atan(long double x);
```

The following code explains the use of `atan()`

function in C++. It returns the angle value in radians by default. This value can be converted to degrees, as shown:

#include <iostream> #include <cmath> using namespace std; int main() { double input = 57.6; double resultRadians = atan(input); double resultDegrees = (resultRadians * 180) / M_PI; //M_PI gives the value of Pi in C++ and is defined in the cmath library cout << "atan(50.6) = " << resultRadians << " radians" << endl; cout << "atan(50.6) = " << resultDegrees << " degrees" << endl; return 0; }

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