rhumb

例句：

1. 1. The curve of the road is quite steep.
   这条路的曲线相当陡峭。
2. 2. The radius of the circle is 5 units.
   这个圆的半径是5单位。
3. 3. The radius of the earth's orbit around the sun is about 63,000kilometers.
   地球围绕太阳的轨道半径大约是63,000公里。