求证：sinθ（1+cos2θ）=sin2θcosθ

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问题解答题

答案

证明：∵左边=sinθ•2cos²θ=（2sinθcosθ）cosθ=sin2θcosθ=右边，所以，原等式成立．

阅读理解

阅读短文，判断对(√)错(×)。

I am a girl. My name is Jenny. I am fifteen. I am a student, I like to play with my ball. In the morning, I go

to school. In the afternoon, I finish school at three-thirty. I walk home. After supper, I do my homework.

( ) 1. Jenny is twenty-five.

( ) 2. Jenny likes to play with her doll.

( ) 3. In the morning, Jenny does her homework.

( ) 4. Jenny finishes school at three-thirty.

判断题

带式输送机运转中，人员可以在非人行道一侧及空间较小的输送带下清煤。