# What is the usage of the tan2 function in C++?

The tan2 function is a mathematical function in C++ used to calculate the tangent value of two given parameters. Specifically, the tan2 function takes two parameters, x and y, and returns the tangent value of y/x. What sets it apart from the standard tan function is that it can accept two parameters instead of just one.

The prototype of the tan2 function is:

```
double tan2(double y, double x);
```

The parameters y and x are used to calculate the tangent value, with the function returning the value of tangent of y/x. It is important to note that the result is undefined if x is equal to 0.

Example of usage:

```
#include <iostream>
#include <cmath>
int main() {
double y = 3.0;
double x = 4.0;
double result = std::tan2(y, x);
std::cout << "The result is: " << result << std::endl;
return 0;
}
```

In the example above, we calculated the result of the tangent value y/x and displayed the result.