tangent

離題、岔開的話題常與 on a 連用

He went off on a tangent about his childhood pets.

他突然離題，講起小時候養的寵物。

切線、切面數學

Draw a tangent to the circle at that point.

在那一點畫出這個圓的切線。

正切數學

The tangent of forty-five degrees equals one.

四十五度的正切值等於一。

相切的、切線的數學

The line is tangent to the curve at the origin.

這條直線在原點與曲線相切。

離題、扯遠口語

Sorry, I keep going off on a tangent during meetings.

抱歉，我開會時老是扯遠。