a) Có góc DBH = góc AHB ( cùng = 90 º do cùng vuông góc BC )

mà 2 góc này ở vị trí so le trong nên BD song song AH. 

Lại có BD = AH ( gt ) nên AHBD là hbh

 vậy AB song song DH ( theo tính chất hbh ) 

b) Xét tam giác ABH có góc BAH = 35 º ( gt )

góc AHB = 90 º do AH vuông góc BC. 

Vậy góc ABC = 180º-90º-35º = 55º . 

Do đó góc ACB = 180º - góc ABC - góc BAC 

= 180º-90º-55º = 35º

dễ

D ở đâu vậy bạn

có góc DBH=ABH(=90do)

ma 2 goc lai o vi tri solr=e trong do AH cat AB va HE

suy ra Ab// HE

1. When did she began working in this company?

=> how long has she worked in this company?

2. This is the first time I have seen such a tall man .

=> this is ( ??? )

3. This is the first time I have eaten such a good meal

.=> I haven't eaten such a good meal before

4. The last time she gost an a in English is last month

=> she hasn't gost an a in English since last month

5. Has you ever seen an elephant before?

=> is this the first time you ever seen an elephant ?

6. It is 3 years since I last taught in BHH school

=> I haven't taught in BHH school for 3 years

7. The last time she traveled by bus was 6 years ago

=> it is 6 years since she traveled by bus

8. I haven't meet a fatter man than this man

=> this is the first time I have met a fatter man than this man

9. She began conducting the survey 3 days ago

=> she has conducted the survey for 3 days

10. He has written that novel 6 months

=>he started writing that novel 6 months ago

#Yumi

t nghĩ c2 là

This is the tallest man that i have ever seen