Okay, the user wants me to translate "quarter-circle" into Persian. Let me think about the correct term.
First, "quarter" in Persian is "چهارم" or "چهار چهارم" but in mathematical terms, it's often "چهارم" or "چهار چهارم" might be more precise. Wait, actually, a quarter-circle is a quarter of a circle, so in geometry, it's commonly referred to as "چهارم دایره" or "ربع دایره". "ربع" means a quarter, so "ربع دایره" is the term used in Persian for quarter-circle. Let me confirm that. Yes, "ربع دایره" is the correct translation. The user provided the translation rules, so I need to make sure I follow them. Since the input is in English, I should translate it. The output should be only the translation without any explanations. Alright, so the answer is "ربع دایره".