Formula symbol confusion

[Guest]

Hi, I am struggling with the second part of this formula in the image. Could someone please explain to me what the meaning of it is. E.g. I know the [tex]\sqrt{x}[/tex], but is the D subtracted? An example would really help. Thank you.

formula.jpg (10.78 KiB) Viewed 1082 times

[Guest]

You have every right to be confused! I suspect that was a printing error and it was supposed to be [tex]H= \frac{D+ d}{2}+ \frac{\sqrt{2}}{D}[/tex].