giu minh di
d= 3,2 cm
r=3/4 m
r=16cm
d =14cm
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Gọi giao điểm của hai đường chéo là O
Độ dài cạnh OA là: \(OA=\dfrac{1}{2}\cdot AC=\dfrac{1}{2}\cdot10=5\left(cm\right)\)
Ta có \(\Delta AOD\) vuông tại A nên ta có:
\(AD^2=OA^2+OD^2\)
\(\Rightarrow OD=\sqrt{AD^2-OA^2}=\sqrt{13^2-5^2}=12\left(cm\right)\)
Mà: \(OD=\dfrac{1}{2}BD\Rightarrow BD=2\cdot OD=2\cdot12=24\left(cm\right)\)
Vậy chọn đáp án A
1.___how long___ have you give up smoking? For about two years.
2.___which___ place is more densely populated-Ha Noi or Ho Chi Minh City?
3.__who__ broke Jane's favorite vase? Her brother did it.
4.__what__ does Mr.Brown do? He's a researcher
5.__how many__ ethnic groups are there in your country?
1. My brother hasn't seen his best friend for nearly five years.
=> It's five years since my brother last met his best friend.
2. When did you start learning English?
=> How long have you studied English?
3. Minh began to collect stamps in 2000.
=> Minh has begun to collect stamps since 2000.
Hok tốt
1. My brother hasn't seen his best friend for nearly five years
=> It's is the first time my brother saw him after nearly five years
2. When did you start learning English?
=> How long have you learnt English ?
3. Minh began to collect stamps in 2000
=> Minh has collected stamp from 2000 .
1.Where is your younger brother?”, Minh asked me.
➔ Minh asked me where my younger brother was.
2. “Say goodbye to my grandparents”, they said.
➔ They asked me to say goodbye to their grandparents.
3. “ Did Mr Bean send the letter to you?”, Mai asked him.
➔ Mai asked him if Mr Bean had sent letter to him.
4. “Where is the best place to eat pizza?”, Oanh asked.
➔ Oanh asked where the best place to eat pizza was.
5. “What do you want for dinner tonight, Ly?”, he asked.
➔ He asked Ly what she wanted for dinner that night.
6. Jun asked me, “Did you go to work yesterday?”
➔ Jun asked me if I had gone to work the day before.
7. My sister asked him, “How long have you learnt English?”
➔ My sister asked him how long he had learnt English.
8. She wanted to know, “Are you a teacher?”
➔ She wanted to know if I was a teacher.
9. My grandfather asked her, “Does you enjoy your job?”
➔ My grandfather asked her if she enjoyed her job.
10 .He asked, “When did you buy it?”
➔ He asked me when I had bought it.