Предмет: Геометрия, автор: romanyukdarya2008

ДАЮ 30 БАЛЛОВ
в равнобедренном треугольнике ABC с основанием АС проведены медианы АК и СМ. докажите, что угол АМС равен углу СКА

Приложения:

Ответы

Автор ответа: irina7777747

1

Ответ:

Треугольник АВС, АВ=ВС, АМ и СК медианы, уголА=уголС, АК=КВ=ВМ=МС, треугольник АМС=треугольник АКС по двум сторонам (АК=МС, АС - общая) и углу между ними (уголА=уголС)

рассматривая треугольники:АМС=треугольник АКС(САК)

romanyukdarya2008: спасибо большое, я всё поняла!!!

Предыдущий вопрос

Следующий вопрос

Похожие вопросы

Предмет: Английский язык, автор: ZaicevaN

Слова к тексту «Metals in the Service of Man”.

1. output ['autput] n продукция; выпуск, выработка; горная добыча; производительность, мощность
The output of different products depends on market demand.
2. reason ['rJzn] n причина, основание
There is reason to believe that he is wrong.
3. characteristic ["kxrIktq'rIstIk] a характерный
It’s characteristic of some metals to corrode in the presence of aggressive environments.
4. support [sq'pLt] v поддерживать, выдерживать
Is this bridge strong enough to support heavy lorries?
5. weight [weIt] n вес
One of the biggest loads a bridge has to carry is its own weight.
6. bend (bent, bent) v сгибать (ся)
The pipe was heated and bent at a right angle.
7. destruction [dIst'rAkSn] n разрушение
The destruction of Neftegorsk, a town in the north of Sakhalin, by the earthquake in 1995 was awful.
8. approximately [qp'rOksImItlI] adv приблизительно
Light travels at approximately 186,000 miles per second (300,000 metres per second).
9. mine [maIn] v добывать (руду, уголь)
Coal is mined from deep under ground.
10. pass [pRs] v проходить
The road was too narrow for cars to pass.
11. metallurgist [me'txlqGIst] n металлург
Metallurgists in all countries use the continuous steel smelting (метод непрерывной плавки стали).
12. refining n очистка
Oil has to pass through refining to become usable.
13. purification ["pjuqrIfI'keISn] n очистка
Air purification is provided at all plants and factories.
14. treat v обрабатывать
Wood must be treated with special substances not to be destroyed in the open air.
15. smelting n выплавка, плавка
Metals are separated from ores by smelting.
16. comparatively [kqm'pxrqtIvlI] adv сравнительно
Comparatively few students were eager to take part in the conference.
17. insufficient ["Insq'fISent] a недостаточный
The travellers had insufficient food for ten people.
18. to a considerable extent в значительной степени
Mechanical properties of zirconium depend to a considerable extent on its purity.
19. in spite [spaIt] of несмотря на
Titanium in spite of early recognition of its light weight, strength and corrosion resistance is a relative newcomer to the industrial scene.
20. … as well также
Zirconium has much better corrosion resistance to aggressive environments than stainless steels and is particularly useful at high temperatures as well.
21. nowadays в настоящее время
Nowadays some plastic materials can replace metals.

Прочитайте текст “Metals in the Service of Man”. Выполните следующие задания:

1. Скажите, какую роль играют металлы в жизни человека.
2. Найдите в тексте случаи употребления страдательного залога.

METALS IN THE SERVICE OF MAN

Let us consider why metals play such a great role in man’s activities. Wood and stone are both older in use, yet to a considerable extent they have been replaced by metals. In spite of the great progress of chemistry and increasing output of plastic materials metals are still used for most of machines, structures and instruments. If there were no metals, no railway, airplane, car, electric motor, turbine or pipeline could operate.
The reason for the increased use of metals is to be found in their characteristic properties. The most important of these properties is their strength or ability to support weight without bending or breaking. Resistance to atmospheric destruction, plasticity and the ability to be formed into desired shapes are remarkable as well. Some metals have also special properties – two of which are the ability to conduct electric current and the ability to be magnetized.
Nowadays we know that over three quarters of existing elements are metals. We know approximately over 80 metals and several thousand alloys.
Most metals are usually found in nature as minerals or ores, where they exist in chemical combinations with other substances. Metallic ores contain metals combined with oxygen, sulphur or other metals.
Ores are usually mined and passed to the metallurgist for refining and purification. The ores are treated by fire or chemically by the process called smelting. Ores have to pass through this very complicated process before pure metals are obtained.
But pure metals are comparatively seldom used because they are rather expensive and their strength is generally insufficient for the purposes of to-day. The most important way in which the strength of metals can be increased is alloying. Alloys are the most important engineering materials. Alloys are obtained by adding various metals or non-metals to the main metallic element.

1 год назад

Предмет: Русский язык, автор: poltoranina1

антоними к словосочетаниям: вариться в собственном соку,на песке строить,нить Ариадны,отставной козы барабанщик,шапками закидать

1 год назад

Предмет: Русский язык, автор: alawa

укажите каким членом предложения являются подчеркнутые слова в предложении поезд прибыл в семь часов

1 год назад

Предмет: Английский язык, автор: polina2167

Complete the sentences using the words from the box.
Forms: off, out, on around, up
1. My friend is going to England. I'm going to see her ....
2. Look...! There's a car coming.
3. How was the exam? How did you get...?
4. I found ... that he was moving to Australia.
5. He tried to give ... smoking but he couldn't.
6. When I touched him on the shoulder, he turned ....

8 лет назад

Предмет: Русский язык, автор: печатает123

Наша Таня громко плачет уронила в речку мячик Тише Танечка не плачь не утонет в речке мяч
Основная мысль
ключевые слова
Тема
срочно!!!!!

8 лет назад