radius

半径

円や球の中心から外側の縁までの距離。

やさしい英語で： The distance from the center of a circle or ball to its outer edge.

• The radius is five centimeters.
• Double the radius to find the diameter.
• Several villages lie within a ten-kilometer radius of the school.

使い方： a radius of something (The circle has a radius of four centimeters.); within a radius of something (Deliveries are free within a radius of five kilometers.)

よく使う表現： radius of something, within a radius, five kilometer radius

半径

円や球の中心から外側の縁までを結ぶ直線の部分。

やさしい英語で： A straight line from the center of a circle or ball to its outer edge.

• Draw a radius from the center.
• Each radius meets the circle at its edge.
• The diagram shows two radii forming an angle.

使い方： the radius of something (Draw a radius of the circle in red.)

よく使う表現： draw a radius, radius of something, circle radius

橈骨

人の前腕や動物の前脚の下部にある、二本の主要な骨の一つ。

やさしい英語で： One of the two main bones in the lower part of an arm or animal foreleg.

• She broke her radius.
• The surgeon examined the lower end of the radius.
• The animal has a short radius beside its ulna.

よく使う表現： radius and ulna, fractured radius, distal radius