Okay, the user wants me to translate "quarter-circle" into German. Let me think. The term "quarter-circle" refers to a quarter of a circle, which in geometry is called a "Viertelkreis" in German. I should check if that's the correct term. Yes, "Viertelkreis" is the standard translation. Since the original content isn't in German, I need to provide the translation. The user specified to output only the translation without any explanations, so I'll just write "Viertelkreis".