Today just a short note. Recently I've been working on a XNA project. In my project I needed to rotate line. I used that calculation:

```
float angle = (float)Math.Atan2(point2.Y - point1.Y, point2.X - point1.X);
```

to calculate the angle in radians and the use **angle **in SpriteBatch.Draw() method. Recently I found **MathHelper** class from XNA. I has a lot of useful methods. One of those is:

```
MathHelper.ToRadians(90);
```

This is what I was looking for!