Tìm nghiệm của phương trình \(\cot \left( {x - \dfrac{\pi }{3}} \right) = \dfrac{{\sqrt 3 }}{3}\)?
\(x = \dfrac{\pi }{3} + k\pi ,k \in Z\).
\(x = \dfrac{\pi }{2} + k2\pi ,k \in Z\).
\(x = \dfrac{{2\pi }}{3} + k\pi ,k \in Z\).
\(x = k\pi ,k \in Z\).
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
Ta có: \(\cot \left( {x - \dfrac{\pi }{3}} \right) = \dfrac{{\sqrt 3 }}{3} \Leftrightarrow x - \dfrac{\pi }{3} = \dfrac{\pi }{3} + k\pi \Leftrightarrow x = \dfrac{{2\pi }}{3} + k\pi \,\,\left( {k \in Z} \right)\).
Chọn đáp án C.
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Câu hỏi liên quan
Read the following passage about cultural diversity 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.
Cultural diversity refers to the presence of multiple cultural groups and their practices within a society. It encompasses various aspects such as language, traditions, beliefs, and values. Embracing cultural diversity can lead to a more inclusive and harmonious society, where individuals appreciate and respect differences. This diversity enriches communities by introducing new perspectives, fostering creativity, and promoting mutual understanding.
One significant benefit of cultural diversity is the exchange of ideas and knowledge. When people from different cultural backgrounds interact, they share their unique experiences and insights. This exchange can lead to innovative solutions and improvements in various fields such as science, art, and business. Moreover, cultural diversity can enhance social cohesion by encouraging people to work together and learn from one another.
Education plays a crucial role in promoting cultural diversity. Schools and universities can create inclusive environments by incorporating diverse perspectives into their curricula and encouraging students to engage with different cultures. By doing so, educational institutions help students develop a global mindset and prepare them for a multicultural world. Additionally, exposure to diverse cultures at a young age can reduce prejudices and promote tolerance.
In the workplace, cultural diversity can boost productivity and creativity. Diverse teams bring together individuals with different skills, viewpoints, and problem-solving approaches. This variety can enhance decision-making processes and lead to more effective and innovative solutions. Companies that prioritize cultural diversity also tend to have a more positive work environment and higher employee satisfaction.
Despite its benefits, cultural diversity also presents challenges. Misunderstandings and conflicts can arise when people from different cultural backgrounds interact. To address these challenges, it is essential to promote open communication and cultural competence. By fostering an inclusive culture, societies and organizations can maximize the benefits of cultural diversity while minimizing potential conflicts.
In which paragraph does the writer mention the role of cultural diversity in the workplace?
Cấp độ tổ chức sống nào dưới đây có khả năng trao đổi chất, sinh trưởng, sinh sản và cảm ứng?
Đối với hệ thống khí canh, hệ thống phun sương là:
Về phía các cơ quan nhà nước, những hành vi vi phạm quyền và nghĩa vụ của công dân trong tham gia quản lý nhà nước và xã hội gây ra hậu quả như thế nào?
Chọn ý đúng: Công nghệ năng lượng tái tạo:
Read the following passage about managing change 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.
Growing up in Athens, Greece, Lydia Borsi remembers feeling tested when she tried to deal with mental health issues. Borsi says she had been seeing a therapist for anxiety. But she notes that people in Greece do not openly discuss mental health issues, which also get little attention in general healthcare services. “It was a lot more secretive. And people thought that I was a lot more unique,” Borsi said.
That all changed in 2017 when she moved to the United States to study at the University of Rochester in Rochester, New York. “When I came here, I really liked that people were not afraid to speak up about mental health and say that it’s important,” she said. The university was very supportive of her needs and offered plenty of information. She also became involved with a school group called Active Minds that helps students deal with mental health issues. [A]
Then due to the spread of the novel coronavirus, the University of Rochester had to move all its classes and some of its mental health resources online. Luckily, Borsi was able to connect with a mental health expert outside the school, in the local community. [B]
But as many of her American friends returned home, Borsi was stuck. Greece had succeeded in limiting the spread of the virus within its borders, but flights there from the U.S. are barred until July. Also, the health crisis has put her plans to seek admission to medical school in Britain on hold. [C] And she is not alone.
[D] In April, Active Minds launched a survey of over 2,000 students at U.S. colleges and universities. The study found that over 80 percent of those asked said the coronavirus crisis had negatively affected their mental health. One in five said it has affected them severely.
Laura Horne, chief program officer at Active Minds, says the findings are especially troubling given that the crisis is only going to make it harder for colleges and universities to help these students. “Colleges and universities had to pivot rather quickly to respond to COVID-19 and figure out all facets of university life, including mental health services. Now they have to figure out how to communicate with students,” Horne said.
Frank Chen is a Houston, Texas-based psychiatrist who has worked with college-age young adults. He points out that individuals at that age are in an important stage of their mental development. And college can be a difficult experience for students with or without mental health issues, as they balance work, studies, and personal relationships. Adding a major world event, like the spread of the coronavirus, makes it very difficult to predict what the long-term psychological effects might be. “I don’t think that there’s another event in the history of the people who are alive now that can really measure up to this,” said Chen.
The word ‘barred’ in paragraph 4 is closest in meaning to
Read the following passage about the Pathways from Today's Actions to Tomorrow's World 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.
As we stand at the crossroads of environmental decision-making, the actions we take today will shape our world in 2050. Scientists warn that we're skating on thin ice with current consumption patterns and carbon emissions. Global temperatures could rise by 2-4 degrees Celsius unless significant changes occur within the next decade. Many countries have pledged to achieve carbon neutrality by 2050, but these promises require immediate implementation. Individual choices in transportation, energy usage, and consumption can collectively influence whether future generations inherit a sustainable planet or face severe climate consequences.
[I] Technological innovation represents our greatest hope for addressing environmental challenges by 2050. [II] Renewable energy sources like solar and wind are becoming increasingly affordable, potentially replacing fossil fuels entirely within thirty years. [III] Electric vehicles may dominate transportation networks, while vertical farming could transform food production in urban areas. [IV] However, these technological solutions must be developed and deployed equitably to avoid creating new disparities between wealthy and developing nations.
Social structures will undergo dramatic transformation by 2050 as demographic shifts reshape communities worldwide. Aging populations in developed countries will necessitate new approaches to healthcare, retirement, and social support systems. Meanwhile, climate migration may force millions to relocate from vulnerable coastal and drought-prone regions. Education systems must evolve to prepare our students for jobs that don't yet exist, emphasizing their adaptability and lifelong learning. Cities will need to become more resilient, incorporating green spaces and sustainable infrastructure to support growing populations.
Economic models must fundamentally change by 2050 to balance prosperity with environmental responsibility. The traditional focus on continuous growth may shift toward measuring success through wellbeing indicators rather than GDP alone. Circular economy principles will likely replace linear production models, with products designed for reuse and recycling. Resource-sharing platforms may become more prevalent, reducing individual consumption while maintaining living standards. Companies implementing genuinely sustainable practices will thrive, while those clinging to environmentally harmful methods may disappear entirely. The transition presents both challenges and opportunities for businesses willing to embrace innovation and sustainability.
Which of the following best summarises the passage?
Một vật được ném theo phương ngang với vận tốc ban đầu là \[{{\rm{v}}_0} = 30\]m/s từ một độ cao h = 80 m so với mặt đất. Lấy \[{\rm{g}} = 10{\rm{m/}}{{\rm{s}}^{\rm{2}}}\]. Bỏ qua sức cản của không khí. Tính thời gian rơi và tầm xa của vật.
She is so absent-minded. She _______________ her cell phone three times.
Căn cứ theo nguồn gốc, tình trạng thất nghiệp được chia thành mấy loại hình?
Câu nào sau đây nói không đúng về yêu cầu của hệ thống lái?
Hô hấp tế bào (hô hấp hiếu khí) bao gồm mấy giai đoạn?
Xét hàm số \(y=\text{cos}x\) trên khoảng \(\left( \frac{\pi }{5};\frac{4\pi }{3} \right)\) đồng biến trên khoảng có độ dài là
Khi bón phân quá liều lượng, cây sẽ bị héo và chết do đâu?
Cho biết kết quả khi chạy đoạn chương trình sau:
s = 0
for i in range(3):
s = s+2*i
print(s)
Khai triển nhị thức Newton của \({(3 - y)^4}\) là?
Read the passage carefully
1. Millions of people are using cellphones today. In many places, it is actually considered unusual not to use one. In many countries, cellphones are very popular with young people. They find that the phones are more than a means of communication - having a mobile phone shows that they are cool and connected.
2. The explosion in mobile phone use around the world has made some health professionals worried. Some doctors are concerned that in the future many people may suffer health problems from the use of mobile phones. In England, there has been a serious debate about this issue. Mobile phone companies are worried about the negative publicity of such ideas. They say that there is no proof that mobile phones are bad for your health.
3. On the other hand, medical studies have shown changes in the brain cells of some people who use mobile phones. Signs of change in the tissues of the brain and head can be detected with modern scanning equipment. In one case, a traveling salesman had to retire at young age because of serious memory loss. He couldn't remember even simple tasks. He would often forget the name of his own son. This man used to talk on his mobile phone for about six hours a day, every day of his working week, for a couple of years. His family doctor blamed his mobile phone use, but his employer's doctor didn't agree.
4. What is it that makes mobile phones potentially harmful? The answer is radiation. High-tech machines can detect very small amounts of radiation from mobile phones. Mobile phone companies agree that there is some radiation, but they say the amount is too small to worry about.
5. As the discussion about their safety continues, it appears that it's best to use mobile phones less often. Use your regular phone if you want to talk for a long time. Use your mobile phone only when you really need it. Mobile phones can be very useful and convenient, especially in emergencies. In the future, mobile phones may have a warning label that says they are bad for your health. So for now, it's wise not to use your mobile phone too often.
Choose an option (A, B, C, or D) that best answers each question:
According to paragraph 3, which is TRUE about the salesman?
Một chiếc thuyền xuôi dòng sông từ A đến B hết 2 giờ 30 phút. Khi quay ngược dòng từ B đến A mất 3 giờ. Vận tốc của nước so với bờ sông và vận tốc của thuyền so với nước là không đổi. Tính thời gian để một khúc gỗ tự trôi từ A đến B là bao nhiêu?.
Xác định ý đúng: Đặc điểm nào không đúng với vai trò của nội thương?
Read the following passage about world festivals and mark the best answer to the questions from 11 to 18.
World festivals have a big impact on young people today. Festivals such as Christmas, Diwali, Halloween, and Chinese New Year are celebrated across the globe, bringing people together. Young people especially enjoy these events because they offer a chance to have fun, learn about different cultures, and develop a global mindset.
Festivals help young people appreciate diversity. Attending a festival from another culture teaches them new traditions, food, music, and art. For example, attending the Rio Carnival or the Holi Festival of Colors can give young people an exciting experience of new cultures. They learn to respect and understand people from different backgrounds, which is important in today’s world.
Another impact is that festivals allow young people to express themselves creatively. Many festivals include costumes, dances, and music that encourage self-expression. For instance, during Halloween or a music festival like Coachella, young people often wear creative outfits or costumes that reflect their personalities. This makes them feel confident and allows them to experiment with new styles.
Festivals also offer opportunities for young people to connect with others. Meeting people at festivals, whether in person or online, helps them build friendships and networks. Social media plays a big role in this, as many young people post about their experiences, spreading awareness of the festivals they attend.
Overall, world festivals provide many learning and social experiences for young people, helping them grow into more open-minded and creative individuals.
In which paragraph does the writer mention the cultural diversity that young people can experience through festivals?