题干

给出下列命题:

①在直角三角形ABC中,已知两边长3和4,则第三边长为5;

②三角形的三边a、b、c满足a2+c2=b2,则∠C=90°;

③△ABC中,若∠A:∠B:∠C=1:2:3,则△ABC是直角三角形;

④△ABC中,若a:b:c=1: 3 :2,则这个三角形是直角三角形;

其中,正确命题的个数为(   )

A:1个

B:2个

C:3个

D:4个

上一题 下一题 0.0难度 选择题 更新时间:2020-02-17 05:23:59

答案(点此获取答案解析)

B

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I am not a brave girl, and even a little mouse scares(惊吓) me.1 I’ve been crazy about bungee jumping(蹦极). One day, I found a good place for this exicing2in Thailand by surfing the Internet. I packed my bag and flew there. However, I had no idea how to get to the address listed on the3. I called them and took a taxi, but the taxi driver didn’t know the way, either. He dropped me halfway.

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