cho hình thang ABDC có góc A = góc B= 90 độ , O là điểm trên AB sao cho góc COD = 90 độ , giả sử DO là phân giác của góc D đường thẳng qua góc B vuông góc với DO tại I , cắt CD tại M . Chứng minh :
a)\(OM^2\) = AC.BD và OI .OD = \(\left(\dfrac{AB}{2}\right)^2\) .
b)\(\dfrac{4}{AB^2}=\dfrac{1}{AC^2}+\dfrac{1}{OD^2}\)
cho hình vuông ABC , góc A = 90 độ , trung tuyến AM và đường cao AH . Trên tia AM lấy điểm D sao cho AM=MD .
a) CHỨNG MINH : tứ giác ABDC là hìh chữ nhật.
b) Gọi D' và E theo thứ tự là chân đường vuông góc hạ từ H đến AB,AC, chứng minh : tứ giáC AD'HE là hình chữ nhật .
c)Chứng minh; D'E vuong góc vs AM
I/Put the following sentences into reported speech
1: He said : " We shall go with him "
2: He said :" I can't find the key"
3: He said : " I am going to the university tonight"
4:He said to her : " I will get married if my mother agrees "
5: He says to me : " I will get married if my mother agrees "
6: I said to him : " Your bike has been stolen "
7: He says :" The river is rising early this year"
8:The boy said to me : "I am going to quit school"
9: He says to me : " I'll come as soon as possible"
10: She said : " I'm leaving for Ha Noi tomorrow"
Rewrite these sentences , using reported speech:
1: " I'm going away tomorrow " Minh said....................
2: " I have lost my bag " Hue said..................................
3:" I don't understand the question " Mary said....................
4: "We are coming to visit some classmates" they said ................
5: " Our family moved to city 3 days ago " they said ............
6: " I have 2 sisters and 1 brother " he said..........
7: " My father is a farmer " Binh said................
8: " I am staying with some my friends now" Mary said............
9: " We were watching at 3 P.M yesterday " they said..........
10: " You will see the doctor tomorrow" Vui said..........