Hello,

I want to find the degrees of a corner C by using the “cosine rule” when I print the returned number, it gives me “Nan”

What’s wrong?

```
var Cdegree = Mathf.Acos( (Mathf.Sqrt(a) + Mathf.Sqrt(b) - Mathf.Sqrt(c)) / 2 * a * b);
print (Mathf.Rad2Deg * Cdegree);
//a,b,c are the 3 lines of the triangle
```