OG11th PS 206 請教

songyeonpp

In the circle about, PQ is parallel to diameter OR, and OR has length 18. What is the length of minor arc PQ?(题目有附饼图，抱歉没办法贴上)

 

请问一下OG的解释，Minor arcs always have twice the measure of their inscribed angles. Arc不是弧？两倍的内接角？

 

请教一下是什么意思？感谢

songyeonpp

Thank you for your reply.

謝謝你的回答

沒錯就是考這個定裡

一条弧所对的圆周角等于它所对的圆心角的一半。

albertes

arc是弧，inscribed angles是指圆周角吧。

因为OG在Math Review里写的是“The number of degrees of arc in a circle is 360."所以貌似是把弧和其圆心角放在一起说了。

Minor arcs always have twice the measure of their inscribed angles。应该就是说弧所对的圆心角是其圆周角的2倍。