共きょう通つう接せっ線せん

noun

common tangent

In geometry, a line that is tangent to two or more curves or surfaces.

• 二ふたつの円えんに共きょう通つう接せっ線せんを引ひく。

  Draw a common tangent to the two circles.

• 共きょう通つう接せっ線せんの方ほう程てい式しきを求もとめなさい。

  Find the equation of the common tangent.