câu 1 : Cho góc nhọn xOy và N là một điểm thuộc tia phân giác của góc xOy. Kẻ NA ⊥ Ox (A∈ Ox).NB ⊥Oy (B ∈Oy) a,CM: NA=NB b,Tam giác OAB là tam giác gì? Vì sao? c,Đường thẳng BN cắt Ox tại D. Đường thẳng AN cắt Oy tại E.CM:ND=NE d,CM:ON ⊥ DE . . câu 2: Cho tam giác ABC cân tại A, Kẻ AH⊥BC (H ∈ BC) a) Chứng minh góc ∠BAH = ∠CAH b) Cho AH = 3 cm, BC = 8 cm. Tính độ dài AC. c) Kẻ HE ⊥ AB, HD ⊥ AC . Chứng minh AE = AD. d) Chứng minh ED // BC. vẽ hình luôn nha

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Exercise 6: Use Relative adverb to combine each pair of sentences below: 1. This is the house. We often stay in this house in summer. .............................................................................................................. 2. I’ll show you the second-hand bookshop. You can find valuable books in this shop. .............................................................................................................. 3. I have not decided the day. I’ll go to London on that day. .............................................................................................................. 4. He was born on the day. His father was away on that day. .............................................................................................................. 5. The book is a telephone directory. We can look up telephone numbers in this book. .............................................................................................................. 6. Mrs. Brown rang Dr. Brown. He was going to carry out an urgent operation at that moment. .............................................................................................................. 7. The airport is the most modern one. We’re going to arrive at this airport. .............................................................................................................. 8. She doesn’t want to speak of the cause. She divorced her husband because of this cause. .............................................................................................................. 9. The days were the saddest ones. I lived far from home on those days. .............................................................................................................. 10.I never forget the park. We met each other for the first time at this park. ..............................................................................................................