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A B A' B' C D
C: Vị trí bóng đèn
AB=BC=1,5m là chiều cao và khoảng cách từ bóng đèn đến đỉnh đầu
B': vị trí mới khi người đó di chuyển
D: vị trí bóng của đỉnh đầu khi người đó di chuyển đến vị trí B'
Ta có
AB=A'B'
\(AB\perp AD;A'B'\perp AD\) => AB//A'B'
=> AA'B'B là hình bình hành => AA'//BB'
Mà AC=AB
=> A'C=A'D (trong tg đường thẳng đi qua trung điểm 1 cạnh và // với 1 cạnh thì đi qua trung điểm cạnh còn lại)
=> AA' là đường trung bình của tg BCD => AA'=BD/2
AA' là quãng đường di chuyển của người, BD là quãng đường di chuyển của bóng đỉnh đầu
Trong 1 khoảng thời gian quãng đường di chuyển tỷ lệ thuận với vận tốc
\(\Rightarrow\frac{AA'}{BD}=\frac{V}{V_{dd}}=\frac{1}{V_{dd}}=\frac{1}{2}\Rightarrow V_{dd}=2\)m/s
hello , my name is Lam . My full name is Pham Nguyen Hoang Lam . My best fiend is An , Huy , Linh and Nam . They like play football , they often play it in your spare time , they play football in stadium . They play football every week . They play sport because it is very interesting . I think should play it to mobilize limbs . tick mình nhé
My favorite cat is so I to collect their pictures. Cats are an animal that has been around for centuries and is now the most popular pet in the world with more than 600 million animals and countless species. In these cats, each cat has its own behavior, shape and color, but all are very cute.
I started collecting pictures of cats about 3 years ago - when I was in 4th grade. Collecting pictures is very simple because when I see beautiful pictures of cats I save on the machine. Then print it out and put it in a notebook - it's called an album. And now I have a beautiful album.
I feel this hobby is very easy and very interesting. In the future, I will continue to do it.
SAU NÀY CÓ BÀI NÀO BẠN CẦN DỊCH THÌ CỨ VÀO GOOGLE TRANSLATE LÀ ĐƯỢC.
Dieu Linh is my classmate. Her hbby is listening to music. She started the hobby when she was 8 years old. She usually searches in the Internet and chooses her favourite songs and she listen. Listening to music makes she feels relax after she finishes her homework. She likes her hobby and she will continue this hobby in the future.
One of my hobbies is listening to music, especially English songs. My hobby started when I was a first – year student at Da Nang University of Technology. I spend much time on it. I can listening when I am doing my housework such as clean the floor, wash clothes, wash dish…or when I sleep…I love Taylor Swift, Rihana…they are great singers. I can learn English vocabulary when listening to English songs and it also make me feel relaxed.
I think it a good hobby and I will never stop it.
In spite of not having a keen on tear-jerking movies, I have to admit that my favorite film is one of those: Along with the Gods: The two worlds. The film starred Cha Tae Hyun who played Kim Ja-hong - a dedicated and brave firefighter. Unfortunately, he died in the line of duty, when trying to save a little girl from a building in fire. However, it was not the end. Accompanied by three guardians, within 49 days after his death, he would have to pass seven trails to reincarnate. But in the last one - the court of Filial Impiety, a grievous secret was revealed about his mistakes in the past. Was he a true paragon? Could he fulfill his dearest hope for seeing his mom for the last time? Generally, the plot is built in an appealing and exhilarating way with a drama twist that creates an emotion explosion at the last minute. In each court, every part of Ja-hong’s life is opened, which delivers meaningful messages not only about the good nature of human but also the eternal love between the mother and her children. Honestly, the film really knows how to touch viewers’ heart. Another factors making it a roaring success are the contribution of well-known celebrities with excellent acting skills and fantas action scenes thanks to amazing visual effects. In brief, Along with the Gods is one of the most impressive fantasy drama film that satisfies me in terms of both content and effect.
ảnh của vật cao 1,5m và ảnh cách vật 1m vì ảnh ảo tạo bởi gương phẳng lớn bằng vật và khoảng cách từ 1 điểm của vật đến gương phẳng bằng khoảng cách từ ảnh của điểm đó tới gương