如果一个三角形一边上的中线也是这边所对的角的平分线，则这个三角形一定是______三角形．
如图，延长AD到E，使DE=AD，连接BE，
∵AD是中线，
∴BD=CD，
在△ADC和△EBD中，
AD=DE ∠BDE=∠CDA BD=DC
∴△ADC≌△EBD（SAS），
∴BE=AC，∠E=∠CAD，
∵AD是角平分线，
∴∠CAD=∠BAD，
∴∠E=∠BAD，
∴AB=BE，
∴AB=AC，
∴△ABC是等腰三角形．
| 完形填空。 | |||
| Table tennis is very popular in China. That is to say, people of all l like playing it. But I like baseball best. Sam is my good friend. His favorite sport is 2 , and he knows about Deng Yaping, Wang Nan and Zhang Yining well. 3 he doesn't know about any famous baseball 4 . Baseball is 5 of the most popular sports in the USA. Children play baseball in fields or parks. Each team 6 nine players. The baseball season usually 7 from April co September. 8 that time, there arc many baseball matches on TV. Many people will 9 them. At the end of' the game season, the two top(一流的) teams play 10 each other. Sport is an important part of our life. What is your favorite sport? Can you tell me? | |||
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