arc subtended by a chord

例句：

1. 1. The arc of the moon casts a long shadow on the ground.
   月亮的弓形轨迹在地面上投下了长长的影子。
2. 2. The arc of the river is breathtakingly beautiful.
   河流的弓形部分令人叹为观止的美丽。
3. 3. The arc of the roof is perfect for hiding things.
   屋顶的弓形部分非常适合藏东西。