如图，PA、PB是⊙O的切线，切点为A、B，若OP=4，PA=23，则∠AOB的度数为

题干

如图，PA、PB是⊙O的切线，切点为A、B，若OP=4，PA=23，则∠AOB的度数为（　　）

A：60°

B：90°

C：120°

D：无法确定

上一题下一题 0.0难度选择题更新时间:2018-03-13 09:28:07

C

注意：1. 短文可适当选用表格里的参考词汇，也可适当发挥；2. 短文要求表达正确，语句通顺，行文连贯：3. 短文次数要求在50词左右。

Seasons	spring	summer	autumn	winter
Weather	Warm, windy	Hot, sunny	Cool sunny	Cold snowy
Activities	Fly kites, plant trees	Go swimming, eat ice cream	Pick apples, go on a picnic	Make a snowman, play in the snow
Clothes	Shirt, jacket, pants	T-Shirt, short dress skirt	jacket, pants, shirt	Coat hat socks gloves scarf
……	…	…	…	…

参考句型：It's…；I often…；I can…；I can wear…

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There are four seasons in a year. My favourite season is