题目

满足下列条件△ABC，不是直角三角形的是( )A.∠A＝∠B+∠C B.∠A:∠B:∠C＝1：1：2C.＝ D.a:b:c＝1:1:2 答案：【答案】D【解析】根据直角三角形的判定和勾股定理的逆定理即可判断．A、∠A＝∠B+∠C可得∠A＝90，△ABC是直角三角形；B、∠A:∠B:∠C＝1：1：2，可得∠C＝90，△ABC是直角三角形；C、＝，可得△ABC是直角三角形；D、a:b:c＝1:1:2不能得到△ABC是直角三角形；故选：D．The TV organizers ________ to find four musicians who could act as well as sing, but they could only find one who was good enough.A. had planned B. were planningC. have planned D. are planning