题干

将含有30°角的直角三角板OAB如图放置在平面直角坐标系中,OB在x轴上,若OA=2,将三角板绕原点O顺时针旋转75°,则点A的对应点A′的坐标为(  )


A:( 3 ,﹣1)

B:(1,﹣ 3

C:( 2 ,﹣ 2

D:(﹣ 22

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C

同类题2

      Students these days often have a lot of worries. Sometimes they have problems with their schoolwork, and sometimes with their friends.      Some people think the worst thing is to do nothing. Laura Mills, a teenager from Washington, agrees. “Problems and worries are normal in life,” says Laura. “But I think talking to someone helps a lot. If we don't talk to someone, we'll certainly feel worse.”
    Laura once lost her purse, and worried for days. She was afraid to tell her parents shout it. She even walked three miles to school each day because she didn't have any money. She just kept thinking. “If I tell my parents, they'll be angry!” But in the end, she talked to her parents and they were really understanding. Her dad said he sometimes made careless mistakes himself. They got her a new purse and asked her to be more careful. “I will always remember to share my problems in the future!” Laura says.
       Robert Hunt advises students about common problems. He feels the same way as Laura. “It is best not to avoid our problems. We should always try to solve (解决) them.” He thinks that you can first find someone to talk to. This person doesn't need to be an expert (专家) like himself. Students often forget that their parents have more experience than them, and are always there to help them.
    In English, we say that sharing a problem is like cutting it in half. So you're halfway to solving a problem if you talk to someone about it!