radius

/ˈreɪdiəs/

the length of a line segment between the center and circumference of a circle or sphere

中文释义：半径；半径范围

The radius of the circle is half of its diameter.

圆的半径是其直径的一半。

The explosion could be felt within a radius of five kilometers.

爆炸在五公里半径范围内都能感觉到。