cho Oz là tia phân giác của góc nhọn xOy. trên tia Ox, Oy lần lượt lấy các điểm A,B sao cho OA=OB. gọi C là điểm trên tia Oz sao cho OC>OA. tia AC cắt tia Oy tại D, tia BC cắt tia Ox tại E
a/ chứng minh tam giác OAC= tam giác OBC
b/ chứng minh rằng tam giác OAD=OBE
c/ chứng minh rằng OC vuông góc với AB
d/ gọi M là trung điểm của đoạn thằng DE. chứng kinh rằng M thuộc tia Oz
AI LÀM ĐƯỢC LÀM DÙM LUÔN, NHỚ VẼ HÌNH
Read the following passage and then answer the questions
We send young people of different nationnalities on expeditions around the world. Our volunteers get the chance to work with local people to learn about different cultures
There are ten expeditions every year. Each expedition lasts for ten weeks and takes 150 volunteers.
They go to countries such as Chile, Namibia, Mongolia and Viet Nam.Some of our volunteers work with local people to provide important facilities, for example, building schools. Others work in national parks or help scientists to do environmental research
These adventurous, young people come from all over the world. To become a volunteer you have to be between 17 and 25; you have to speak some English and you also have to be enthusiastic, flexibleand hard-working members of a team
1. Who goes onexpeditions?
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2. How many expeditions are there every year?
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3. How long does each expedition last?
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4. Which language must we know to become a volunteer?
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5. What do the volunteers help the scientists?
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