Cho hình lăng trụ đứng ABC.A'B'C' có đáy là tam giác ABC vuông cân tại A, BC=2CC'.Gọi I,K lần lượt là trung điểm của BC và A'I. Chứng minh:
a) B'C' vuông góc (A'AI).
b) AK vuông góc (A'BC).
c, Gọi K là hình chiếu vuông góc của A trên AC. CM: B,H,K thẳng hàng
Ai cố giúp mình cả 3 câu vs, đề khó wa:)))
1.Cho hình chóp S.ABCD có đáy ABCD là hình bình hành và M,N,P lần lượt là trung điểm các cạnh AB,CD,SA. Q là 1 điểm thuộc đoạn SP.
a, Xác định thiết diện của hình chóp cắt bởi ( ∝) đi qua Q và song song với (SBN)
b, Xác định thiết diện của hình chóp cắt bởi ( Ф) đi qua MN song song với (SAD)
2. Cho lăng trụ ABC.A'B'C'. Gọi M,N,P là trung trọng tâm các tam giác AA'B, CA'C', CBC'
a, Xác định giao tuyến 2 mặt phẳng (ABC) và (BA'C')
b, Chứng minh MN // (BA'C'), (MNP) // (BA'C')
c, Xác định thiết diện của lăng trụ khi cắt bởi mặt phẳng (MNP) Tính diện tích thiết diện biết tam giác BA'C' là tam giác đều cạnh a
3, Cho hình hộp ABCD.A'B'C'D' có tất cả các mặt là hình vuông cạnh a. Trên các cạnh AB,CC',C'D' và AA' lấy các điểm M,N,P,Q sao cho AM = C'N = C'P = AQ = x ( 0 <= x <= a)
a, Chứng minh M,N,P,Q đồng phẳng và Mp,Nq cắt nhau tại 1 điểm cố định
b, Chứng minh MNPQ đi qua 1 đường thẳng cố định
c, Dựng thiết diện của hình hộp khi cắt bởi (MNPQ). Tìm GTLN và GTNN của chu vi thiết diện
1. Cho hai dãy số \(\left(x_n\right)=\frac{\left(n+1\right)!}{2^n}\) và \(\left(y_n\right)=n+sin^2\left(n+1\right)\) dãy số (xn) và y(n) là dãy số tăng hay giảm?
2. Cho dãy số (un) được xác định bởi \(u_1=3\)và \(u_{n+1}\) = \(\frac{u_n}{4}\), ∀n ≥1. Tìm số hạng tổng quát của dãy số
3. Cho dãy số \(\left(u_n\right)=\frac{3n-1}{3n+7}\) . Dãy số \(\left(u_n\right)\) bị chặn dưới, chặn trên hay không bị chặn trên hoặc chặn dưới
III. Read the text and decide whether the sentences are true (T) or false (F)
USAID IN Vietnam
Assisting persons with disabilities has long been one of the top priorities for the U.S. Government in Vietnam. Since 1989, with the establishment of the U.S. Agency for International Development’s (USAID) Leahy War Victims Fund (LWVF), USAID is working to increase the availability of and access to a wide variety of programs benefiting people with disabilities in conflict-affected countries.
In Vietnam, U. S. assistance has helped address medical needs and support the inclusion of Vietnamese with disabilities into all aspects of society. The U.S. Government has contributed more than $80 million in assistance to persons with disabilities, has improved the lives of more than 30,000 persons with disabilities, and has strengthened the Government of Vietnam’s capacity to provide high quality services to those in need. USAID has provided rehabilitation services for tens of thousands of persons with disabilities, education and vocational training including information technology, job placement, supporting parent associations to expand the advocacy for disability issues, and support for the development of legal codes to improve physical accessibility for persons with disabilities in public buildings.
USAID'S work supporting persons with disabilities is also viewed by many as contributing to successful US-Vietnam cooperation to overcome the painful past shared by the two countries. Program activities work in three areas: policy advocacy and coordination, direct assistance including occupational and physical therapy and providing assistive devices, and health systems strengthening, to provide quality disabilities-related care and treatment. Persons with disabilities have been more readily integrated into society by improving their access to health, education and social services. USAID programs support local governments in implementing the national disability law and the U.N. Convention on the rights of Persons with disabilities, and influencing public policies that affect the lives of persons with disabilities.
1. USAID was established in 1989 _____
2. USAID aims to make various programs benefiting all people in conflict-affected countries ___________
3. Addressing medical needs of Vietnamese people is the priority of U.S assistance in Vietnam ___________
4. American government has made an $80 million contribution to help disabled people in Vietnam __________
5. Thanks to USAID, more high quality services are provided to disabled people in Vietnam __________
6. USAID has helped to rehabilitate only a limited number of persons with disabilities in Vietnam __________
7. USAID work makes a great contribution to the success of US-Vietnam cooperation ___________
8. The main focus of USAID activities is providing direct assistance with occupation replacement and health treatment for the disabled. ___________
9. Having better access to health, education and social services, the disabled in Vietnam have become more integrated into society ___________
10. Thanks to USAID programs, the Vietnam's national disability law and the U.N. Convention on the Rights of persons with disabilities have been enforced ___________
I. Rewrite each of the following sentences, using the suggested word.
1. My school has conducted several volunteer programs to raise students' awareness of helping others. (BEEN)
2. My grandfather became deaf when he turned 70 years old. (SINCE)
3. James last visited his mother, who has been living in the nursing home, in December. (NOT)
4. Helen and her boyfriend haven't gone on a date for ages. (IT)
5. When Maria started college, she stopped doing volunteer work. (SINCE)
II. Read the passage and choose the best answer to each of the following questions.
four great reasons for high school students to volunteer
Volunteer work presents a great opportunity for teenagers to prepare for the future, as well as to improve their communities. In addition to boosting socializing skills and awareness of local organizations and social issues, high school students who volunteer often may have an advantage over their peers when headed off to college.
1. Gaining New Skills
With each new volunteer activity, students gain new skills. The skills seem to be basic or trivial at the time of training, but may provide fundamental grounds for future success. For example, For example, by managing the receipt, sorting and distributing the donations from community, school students might learn how to use spreadsheets to keep track of inventory. These skills are a great foundation for a job in management, accounting, or running a small business.
2. Giving Time
One of the most charitable acts anyone can do is donate their time and talents. Students who are busy with after-school sports or work to help support their families and still make time to volunteer on evenings or weekends show their outstanding character and resolve to make a difference. High school students may help to mentor younger ones or to assist with one-time special events held on weekends.
3. Showing Responsibility
Just like going to a job, committing to a volunteer position shows a student's responsibility. High school students should get involved in volunteer programs relating to their hobbies in order to naturally build responsibility. For example, those who love to read can find volunteer opportunities with a local library and those who enjoy sports can coach athletics at an after-school program for children.
4. Adding to the Resume
If a high school student's pre-college resume is limited to summer employment at a local restaurant or a cafe. it might be time to add a few lines. Commitment to community volunteer work over a long time shows that a student is willing to work for something without monetary compensation, including a college internship or apprenticeship, which may be a requirement of college programs.
1. According to the passage, who is volunteer work beneficial to?
A. high school students
B. students' communities
C. both students and communities
D. none of them
2. The word 'trivial' in paragraph 2 most closely means ________
A. important
B. significant
C. of little importance
D. fundamental
3. According to the passage, what job will the students' skill of using spreadsheets be useful to?
A. a manager
B. an accountant
C. a business owner
D. all of them
4. Why should busy students make their time to volunteer?
A. to demonstrate their excellent quality
B. to show their outstanding outcomes
C. to support their families
D. to develop their talents
5. According to the passage, what volunteer programs help to develop students' responsibility?
A. The programs are related to their future jobs
B. The programs are related to their interests
C. The programs are available after school
D. The programs are held by their local library
6. What volunteer work may be suitable for a student who likes sports?
A. working in a local library
B. joining a football team in their school
C. being a sport instructor at a primary school
D. coaching a football program for children after school hours
7. The phrase 'it might be time to add a few lines' in paragraph 5 most closely means________
A. Some more lines should be added in your resume
B. Much volunteer work must be included in your resume
C. You might spend more time to write your resume
D. Your resume should include your experience in volunteering
8. What may be a requirement of college programs for their future students?
A. being able to work over time
B. agreeing to work as a paid apprentice
C. being willing to work without being paid
D. being employed before
III. Read the text and decide whether the sentences are true (T) or false (F)
USAID IN Vietnam
Assisting persons with disabilities has long been one of the top priorities for the U.S. Government in Vietnam. Since 1989, with the establishment of the U.S. Agency for International Development’s (USAID) Leahy War Victims Fund (LWVF), USAID is working to increase the availability of and access to a wide variety of programs benefiting people with disabilities in conflict-affected countries.
In Vietnam, U. S. assistance has helped address medical needs and support the inclusion of Vietnamese with disabilities into all aspects of society. The U.S. Government has contributed more than $80 million in assistance to persons with disabilities, has improved the lives of more than 30,000 persons with disabilities, and has strengthened the Government of Vietnam’s capacity to provide high quality services to those in need. USAID has provided rehabilitation services for tens of thousands of persons with disabilities, education and vocational training including information technology, job placement, supporting parent associations to expand the advocacy for disability issues, and support for the development of legal codes to improve physical accessibility for persons with disabilities in public buildings.
USAID'S work supporting persons with disabilities is also viewed by many as contributing to successful US-Vietnam cooperation to overcome the painful past shared by the two countries. Program activities work in three areas: policy advocacy and coordination, direct assistance including occupational and physical therapy and providing assistive devices, and health systems strengthening, to provide quality disabilities-related care and treatment. Persons with disabilities have been more readily integrated into society by improving their access to health, education and social services. USAID programs support local governments in implementing the national disability law and the U.N. Convention on the rights of Persons with disabilities, and influencing public policies that affect the lives of persons with disabilities.
1. USAID was established in 1989 _____
2. USAID aims to make various programs benefiting all people in conflict-affected countries ___________
3. Addressing medical needs of Vietnamese people is the priority of U.S assistance in Vietnam ___________
4. American government has made an $80 million contribution to help disabled people in Vietnam __________
5. Thanks to USAID, more high quality services are provided to disabled people in Vietnam __________
6. USAID has helped to rehabilitate only a limited number of persons with disabilities in Vietnam __________
7. USAID work makes a great contribution to the success of US-Vietnam cooperation ___________
8. The main focus of USAID activities is providing direct assistance with occupation replacement and health treatment for the disabled. ___________
9. Having better access to health, education and social services, the disabled in Vietnam have become more integrated into society ___________
10. Thanks to USAID programs, the Vietnam's national disability law and the U.N. Convention on the Rights of persons with disabilities have been enforced ___________
I. Use the correct form of the words to complete each of the following sentences
impairment, charity, disability, donate, preference, integration, respectful, campaign, discriminate, appreciate
1. Buses and trains need to reserve some special seats or areas for women with babies, the elderly and the _____________
2. Those who do noisy jobs such as airport ground staff or construction workers for a long time are likely to have hearing __________
3. It is crucial for teenagers to participate in _____________ work of any kind. That helps them learn how to care and share.
4. Both parents and teachers need to teach children to have a __________ attitude to the elderly.
5. Making a small __________ to a charity helps young people be aware of the value of money.
6. To many students, working with a tutor is ___________ to working with a peer.
7. Jane's mother always ___________ her attempt to fulfill her duties even when she was not successful.
8. Jaden was involved in planning an election _________ for the president of his country.
9. It is significantto _________ children with special needs into ordinary schools so that they are more accepted by their community.
10. Racial__________ doesn't seem to be ended, even in multicultural countries like America or Canada.
II.Choose the best answer to complete each of the following sentences.
1. A: A new house ___________ for the homeless children.
B: Really? When ___________ it built?
A. has been built / has been
B. built / was
C. was built / was
D. has been built/ was
2.The Prime Minister ___________ our university. He __________ to students about the orientation for their future career early today.
A. has visited / spoke
B. visited / spoke
C. has visited / has spoken
D. visited / was speaking
3. At the last meeting, the Student Union ________ to hold a craft and art exhibition to raise money for the kids who _______ from cancer.
A. has decided / suffered
B. decided / suffer
C. has decided / suffer
D. decided/ suffered4
IV. Find the mistakes
1. Newly-born infants should BE screened for their HEARING in order to receive early TREATMENT if it is IMPAIRMENT.
2. The aircraft OF Malaysia Airlines Flight 370 , which HAS DISAPPEARED on the 8th OF March 2014, HAS not been recovered.
3. The findings of a study show that students HAVE CHANGED their attitude TOWARDS the poor after INVOLVE in some CHARITABLE work.
4>The persons with DISABILITIES in Malaysia will have MORE to smile about because several LOCAL companies are now OFFERED jobs to them.
5. MORE AND MORE organizations have BEEN recently FOUND to have helped the poor and ORPHANS in Vietnam.
6. It is BELIEVED that people are HAPPIER THAN they help OTHERS.