Trong không gian cho ba đường thẳng phân biệt a,b,c. Khẳng định nào sau đây đúng?
Nếu a và b cùng vuông góc với c thì a//b
Nếu a//b và c⊥a thì c⊥b
Nếu góc giữa a và c bằng góc giữa b và c thì a//b
Nếu a và b cùng nằm trong mp(α)//c thì góc giữa a và c bằng góc giữa b và c
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
A sai vì: Nếu a và b cùng vuông góc với c thì a và b hoặc song song hoặc chéo nhau hoặc cắt nhau (cùng nằm trong mặt phẳng vuông góc với c)
C sai vì: Giả sử hai đường thẳng a và b chéo nhau, ta dựng đường thẳng c là đường vuông góc chung của a và b. Khi đó góc giữa a và c bằng với góc giữa b và c và cùng bằng 90o
, nhưng hiển nhiên hai đường thẳng a và b không song song.
D sai vì: Giả sử a vuông góc với c,b song song với c, khi đó góc giữa a và c bằng 90o, còn góc giữa b và c bằng 0o
.
Do đó B đúng.
Đáp án cần chọn là: B
Tài liệu "Bộ Đề Kiểm Tra Học Kì II - Toán 11 - Các Trường THPT Trên Toàn Quốc" tổng hợp các đề kiểm tra từ các trường THPT trên toàn quốc, được biên soạn theo đúng chương trình học. Đề thi bao gồm các dạng bài trắc nghiệm và tự luận, tập trung vào các chủ đề trọng tâm: công nghệ và đời sống, quy trình công nghệ, vật liệu kỹ thuật, và ứng dụng công nghệ trong sản xuất và đời sống. Tài liệu giúp học sinh ôn tập hiệu quả, củng cố kiến thức, rèn luyện kỹ năng và tự tin đạt kết quả cao trong kỳ thi học kỳ I.
Câu hỏi liên quan
Để ca ngợi đất nước Việt Nam tươi đẹp ta có thể làm những hoạt động nào sau đây?
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40.
Biting into a ripe, juicy fruit brings a smile to many people’s faces. But eating that same fruit a week before it is ripe probably wouldn’t be as enjoyable! Unripe fruits are often hard and bitter, but that serves a purpose. The hard exterior of an unripe fruit protects the developing seed inside. After a seed fully develops inside the fruit, the fruit changes color, softens, and gets sweeter to become more attractive to animals and humans. These organisms eat the fruit and spread its seeds, ensuring the plant’s survival and regrowth.
But how does a fruit ripen? The ripening process involves many complex chemical reactions. When a fruit ripens, it goes through a chemical change. A chemical change happens when bonds within molecules break, and the atoms that once formed them regroup into new molecules. Chemical changes are irreversible. Once a fruit ripens, it cannot become unripe again.
One molecule responsible for this chemical change is ethylene. Ethylene (C2H4) is a colorless gas made up of carbon and hydrogen atoms. (I). It is a naturally occurring molecule in the atmosphere. (II). It is also an important plant hormone. (III). Plants release ethylene through the growing tips of roots, flowers, and ripening fruit. (IV). Although ethylene serves other purposes in plants, one of its main purposes is to trigger the chemical reactions that cause fruits to ripen. As the fruit matures, oxygen in the air helps stimulate the production of ethylene. This ethylene production is a signal that begins fruit ripening. For that reason, unripe fruits have low levels of ethylene, while ripe fruits have higher levels of ethylene. Most fruits produce ethylene and respond to ethylene in the atmosphere.
Although fruits require ethylene to ripen, different types of fruits respond to this molecule in two distinct ways: non-climacteric fruits and climacteric fruits. Non-climacteric fruits do not ripen after harvesting. They produce very little ethylene of their own. Climacteric fruits, on the other hand, continue to ripen after they are picked. These fruits produce a large amount of ethylene. Climacteric fruits can also speed up the ripening process of other fruits nearby since they release high levels of ethylene into the air.
Which of the following best paraphrases the underlined sentence: The ripening process involves many complex chemical reactions.
Dòng nào nêu đúng khái niệm về luận cứ trong văn nghị luận?
Từ “tiếng ca” trong “Tiếng ca vắt vẻo lưng chừng núi” là chỉ tiếng hát của ai?
Một vật dao động tắt dần có các đại lượng giảm liên tục theo thời gian là
Read the following passage about Singapore Science Centre and mark the letter A, B, C, or D on your answer sheet to indicate the best answer to each of the following questions from 23 to 30.
The Singapore Science Centre, situated on a sprawling six-hectare site in Jurong, offers a captivating way to explore the wonders of science and technology. Here, visitors can engage with interactive exhibits that make learning both fun and memorable. Clap your hands, and colorful bulbs will light up; spin a wheel, and it will activate a fan. This engaging environment sparks curiosity and fuels the imagination of both children and adults.
The centre boasts more than four hundred exhibits across various fascinating topics, including solar radiation, communication, electronics, mathematics, nuclear energy, and evolution. These exhibits are designed to foster interest in science and technology among the public, making the centre a hub for educational exploration.
Notably, it is the first science centre to be established in Southeast Asia. Officially opened in 1977, the centre now welcomes an average of 1,200 visitors daily, highlighting its enduring popularity and educational value.
The exhibits are thoughtfully arranged across four main galleries: the Lobby, Physical Sciences, Life Sciences, and Aviation. To ensure a fresh and engaging experience, the exhibits are renewed annually, encouraging repeat visits. Visitors are encouraged to interact with the exhibits, as opposed to traditional “hands-off” policies in most museums. Here, pushing buttons, turning cranks, or pedaling mechanisms are all part of the fun and learning experience.
The Discovery Centre, added in 1985, is specially designed for children aged three to twelve, providing an exciting space for young minds to explore and experiment. Most recently, a stone-age exhibit was introduced, showcasing extinct animals and early human life, offering insights into prehistoric times.
With its interactive displays and immersive environment, the Singapore Science Centre continues to inspire a love for science and discovery, making it an unforgettable destination for learners of all ages.
In which paragraph is the annual renewal of the exhibits mentioned?
Xác định: Phần nào của phân tử cholesterol không nằm trong lớp kép lipid?
Nguyên nhân chính phía Đông của Liên Bang Nga không thuận lợi cho phát triển nông nghiệp?
Read the following leaflet and mark the letter A, B, C, or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 7 to 12.
ANNOUNCEMENT OF SCHOOL SPORTS DAY
The School Athletics Department is pleased ___(7)___:
● All athletes ___(8)___ to report at the school field by 08:00 AM on June 10.
● Each team must prepare and submit their entry list for each event. Each athlete is allowed to participate ___(9)___ three events.
● The school will ___(10)___ trophies and medals for the winners in each category.
● ___(11)___ you have any inquiries regarding the event schedule or rules, please contact the Athletics Department.
Typically, all the sports ___(12)___ are concluded by an award ceremony. After finishing all the activities, custom awards, incentives, and more should be given to appreciate the competitors and encourage them to improve.
Hàm số nào dưới đây là hàm số mũ cơ số 3?
Hệ thống chính trị Việt Nam có các đặc điểm nào sau đây?
- Trong mỗi ý a), b), c), d) ở mỗi câu, thi sinh chọn đúng hoặc sai
Trong mặt phẳng tọa độ Oxy, xét parabol \(({\rm{P}}):{\rm{y}} = {{\rm{x}}^2} - 4.\)
Có 6 người sống ở các tầng khác nhau của một tòa nhà 6 tầng: A và B ở căn hộ có 1 phòng ngủ; C, D và E sống ở căn hộ có 2 phòng ngủ; F ở căn hộ có 3 phòng ngủ; căn hộ ở tầng 2 có 2 phòng ngủ; F sống ở tầng thấp hơn D; C sống ở tầng thấp hơn B; căn hộ ở tầng 5 hơn căn hộ ở tầng 3 một phòng ngủ.
A không thể sống ở tầng nào dưới đây?
Để xóa liên kết giữa hai bảng, trong cửa sổ Relationships ta thực hiện ra sao?
Chọn ý đúng: Sự kiện nào không xảy ra trong pha sáng?
Hình ảnh dưới đây mô tả một giai đoạn trong quá trình phân bào ở một loài động vật. Theo lý thuyết, có bao nhiêu phát biểu dưới đây là chính xác?
Read the following passage about lifelong learning and mark the letter A, B, C, or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40.
[I] Lifelong learning is the ongoing, voluntary, and self-motivated pursuit of knowledge for personal or professional development (Knowles, 2020). [II] This concept emphasizes that learning does not stop after formal education, but rather continues throughout an individual's life, adapting to changing circumstances and needs. [III] In today’s fast-paced world, where technology and job markets evolve rapidly, lifelong learning has become increasingly essential. [IV]
One of the primary benefits of lifelong learning is its ability to enhance employability. Individuals who engage in continuous education are more likely to keep their skills relevant and competitive in the job market. According to a report by the World Economic Forum (2021), over 50% of employees will need reskilling due to technological advancements in the coming years. Lifelong learners are better equipped to adapt to these changes, making them more attractive candidates for employers.
Moreover, lifelong learning contributes to personal fulfillment and mental well-being. Engaging in new learning experiences can stimulate the brain, foster creativity, and improve cognitive function. Research indicates that individuals who pursue learning opportunities throughout their lives tend to report higher levels of happiness and life satisfaction (Smith & Johnson, 2019). Whether it is taking a course, learning a new language, or picking up a new hobby, the process of acquiring knowledge can be enriching and enjoyable.
In addition, lifelong learning promotes social engagement and community involvement. Participating in educational programs or community workshops can foster connections with others who share similar interests. This social aspect of learning can enhance one's sense of belonging and support networks, which are crucial for mental health (Jones, 2022).
Overall, lifelong learning is not just an individual responsibility; it requires support from educational institutions, employers, and communities to create an environment conducive to continuous education. By fostering a culture of learning, society can better prepare individuals for the challenges of the future and ensure that everyone has the opportunity to thrive.
Which of the following best summarizes paragraph 3?
Cho mệnh đề sau: … x ∈ ℝ, 4x2 – 1 = 0.
Chỗ trống trong mệnh đề trên có thể điền kí hiệu nào dưới đây?
Một xe máy đang đi với tốc độ 36 km/h bỗng người lái xe thấy có một cái hố trước mặt, cách xe 20 m. Người ấy phanh gấp và xe đến sát miệng hố thì dừng lại. Chọn chiều dương là chiều chuyển động. Tính gia tốc của xe.
Mark the letter A, B, C or D on your answer sheet to indicate the correct option that best fits each of the numbered blanks from 27 to 31.
Speech is one of the most important ways of communicating. It consists of far more than just making noises. To talk and also (27) ___________ by other people, we have to speak a language, that is, we have to use combinations of sounds that everyone agrees to stand for a particular object or idea. Communication would be impossible (28) _________________. Learning a language properly is very important. The basic vocabulary of English is not very large, and not only about 2,000 words are needed to speak it quite well. But (29) ________________, the more precise you can be about their exact meaning. Words are the main thing we use in communicating what we want to say. (30) ________________. (31) _______________ of voice can express many emotions and show whether we are pleased or angry, for instance.