《明史·志·卷十三》
求二半径分：将月亮径分，加影径定分，除以二。
求二半径分置太阴径分，加影径定分，半之。
Ask for the secondary radius ratio: add the moon's radial diameter ratio to the fixed shadow diameter ratio and divide by 2.
<s>[INST] 将以下英文转换为文言文: Ask for the secondary radius ratio: add the moon's radial diameter ratio to the fixed shadow diameter ratio and divide by 2. [/INST] 求二半径分置太阴径分，加影径定分，半之。</s>
将以下英文转换为文言文: Ask for the secondary radius ratio: add the moon's radial diameter ratio to the fixed shadow diameter ratio and divide by 2.
user
求二半径分置太阴径分，加影径定分，半之。
assistant