Предмет: Геометрия, автор: MilenaSh

на стороне АС треугольника АВС выбраны точки D и E так,что отрезки AD и CE равны. Оказалось, углы ADB и BEC тоже равны. докажите,что треугольник ABC-равнобедренный.

Ответы

Автор ответа: Delet15
0

Угол BDE равен углу BED так как их смежные углы BDA и BEC равны. Если углы BDA и BEC равны значит треугольник BDE равнобедренный и стороны BD и BE равны. Отсюда треугольник ABD равен треугольнику BEC по двум сторонам и углу между ними. Значит угол     A равен углу C( углы при основании твеугольника ABC). Треугольник ABC равнобедренный

Автор ответа: ksyushatuma
0

1. треугольник BDE - равнобедреный, тк DB=BE по условию => угол BDE = углу BED, тк в равнобедренном треугольнике углы при основании равны

2. угол ADB = углу CEB - смежные

3. треугольник ADB = треугольнику CEB по 1 признаку ( 2 стороны и угол между ними) 

=> AB=BC => треугольник ABC - равнобедренный

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The Kid Who Cooked
Two years ago, Elliot West was more or less just like any other ten-year-old kid. The only thing that made Elliot any different was that he loved cooking.
But everything changed for Elliot one day when he saw an interesting announcement on the Internet. A TV show called Junior Kitchen Star was holding a contest for kids who enjoyed cooking and baking. Elliot was excited. When he was reading about this show, he didn’t know there were other kids who enjoyed the same hobby as he did. He applied to enter the contest immediately.
To qualify for the contest, Elliot had to win a preliminary round against ten other kids from his town. He won easily with a dish of pasta and scallops. He was in the competition!
Whereas the preliminary round was easy, the TV rounds were incredibly difficult. Elliot had to cook against the clock and with limited ingredients. In one challenge, Elliot had to serve up food for a restaurant full of people. The judges were tough and when they had a negative comment about Elliot’s food, he was trying really hard not to cry.
While the contestants were taking part in the competition, top chefs gave them cooking lessons, and Elliot had a chance to learn even more about cooking at the highest level.
Week by week many contestants were eliminated; only two of them were left for the final. One was Elliot and the other was Charles, the son of Pierre La Fontaine, the famous French chef. Over three stressful hours, Elliot and Charles were creating and preparing a seven-course meal for the judges. So…, the judges all said they loved Elliot’s roast goose served with a red wine sauce. Elliot was declared the winner!
After winning the contest, Elliot’s life did not go back to normal. In fact, he became something of a celebrity. He travelled to schools to give cooking demonstrations and produced his own cooking show on YouTube.
Elliot is twelve now. He’s still just a kid, but he has a very bright future indeed.

Answer the following questions based on the reading passage:
1. How did Elliot hear about the cooking show?
A From his parents
B From the Internet
C From the radio
2. What did Elliot have to do to fit for the contest?
A He had to win a round against local kids
B He had to cook pasta with scallops
C He had to get permission from his parents
3. Which of the following is true?
A The judges in the competition were unfair
B The main competition was just as hard as the qualifying round.
C In the competition, the contestants were given time limits.
4. When the judges criticized Elliot’s food, ________________.
A he found it difficult not to cry
B he couldn’t stand people’s tears
C he cried
5. During the contest, how did Elliot get even better at cooking?
A He found lessons on the Internet
B The judges gave the contestants advice.
C The contestants were given lessons.
6. What do we know about the finals?
A The contestants were asked to cook goose.
B The contestants were given three hours to cook.
C The contestants had to serve three dishes.
7. What happened to Elliot after the competition?
A He went back to school.
B He became quite famous.
C He starred in another TV show.​
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