$\\$
`b,`
+) Qua `C` kẻ $Ch//Ax$ (`Ch` nằm giữa `CA` và `CB`)
`->hat{A}+hat{ACh}=180^o` (2 góc tcp bù nhau)
`->hat{ACh}=180^o - hat{A}`
`->hat{ACh}=180^o - 120^o`
`->hat{ACh}=60^o`
+) `Ch` nằm giữa `CA` và `CB`
`->hat{ACh}+hat{BCh}=hat{ACB}`
`->hat{BCh}=hat{ACB}-hat{ACh}=90^o - 60^o`
`->hat{BCh}=30^o`
+) `hat{BCh}+hat{B}=30^o +150^o=180^o`
mà 2 góc này ở vị trí tcp
$→ Ch//By$
+) $Ch//Ax, Ch//By$
$→ Ax//By$
Vậy $Ax//By$
`b)`
kẻ `Cz`//`Ax`
ta có `hat(xAC)+hat(ACz)=180^o` ( trong cùng phía )
`=>hat(ACz)=180^o-hat(xAC)`
`=>hat(ACz)=180^o-120^o`
`=>hat(ACz)=60^o`
ta lại có `hat(ACz)+hat(zCB)=hat(ACB)`
hay `60^o +hat(zCB)=90^o`
`=> hat(zCB)=90^o-60^o`
`=>hat(zCB)=30^o`
ta có: `hat(zCB)+hat(CBy)`
`=30^o +150^O=180^o`
mà hai góc này ở vị trí trong cùng phía
do đó `Cz`//`By`
mà `Cz`//`Ax`
`=>Ax`//`By( đpcm )`
Giúp mình với, càng nhanh càng tốt. Mình cảm ơn Yêu cầu: Không được chép trên mạng
Mn ơi ai biết giải giúp em với ạ
Nguyên tử X có tổng số hạt là 60, trong đó số hạt n bằng số hạt p. Xác định nguyên tố X.
cách mạng tư sản là gì? Tư sản là gì? vô sản là gì?
Nguyên tử X có tổng số hạt nguyên tử là 28. Số hakt không mang điện nhiều hơn số hạt mang điện dương là 1 hạt. a)Xác định số hạt cấu tạo nên nguyên tử b) Tính khối lượng nguyên tử X theo g,u. Mình sẽ vote 5 sao ạ
............... lm hộ mk vs hứa 5* + ctlhn
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
12/2 và 45/5 so sánh NL:tôi ghét mấy đứa chửi tôi.
Viết 1 bài văn thuyết minh về cái quạt có sử dụng biện pháp nghệ thuật nhân hóa
I- Multiple choice 1. The word jeans comes from a kind of material that ............. . in Europe. a) made b) has made c) was made 2. The material ............. jean was named after sailors from Genoa in Italy. a) called b) has called c) was called 3. At first, jean cloth was made ............. a mixture of things. a) of b) from c) by 4. In the 18th century, plantation workers wore jeans ............. completely from cotton. a) was made b) make c) made 5. Cotton .............with indigo, a dye taken from plants in the Americas and India . a) was dyed b) dyed c) has dyed 6. Indigo ............. jean cloth a dark blue color. a) was made b) make c) made 7. A man called Jacob Davis had the idea of ............. metal rivets to hold the pockets and the jeans together. a) used b) using c) use 8. In 1886, Levis sewed a leather label ............. their jeans. a) in b) on c) above 9. During the time of the World War 2, “waist overalls” ............. to the world by American soldiers. a) introduced b) were introduced c) have introduced 10. In the 1950's, denim became popular ............. young people. a,) with b) to c) for 11. Some schools in the USA banned students .............wearing denim a) with b) from c) of 12. Different styles of jeans ............. to match the 60's fashions. a) designed b) were designed c) had designed 13. Since the worldwide recession of the 1990's, the sale of jeans ............. growing. a) stopped b) has stopped c) was stopped 14. In some countries ............. uniforms is compulsory in schools. a) wear b) to wear c) wearing 15. Vietnamese women ............. very proud of the aodai. a) are b) have been c) were 16. The aodai ............. for years. a) is modernized b) was modernized c) has been modernized 17. A new hospital ............. next year. a) is built b) Will be built c) will build 18. Food ............. direct to the market by trucks. a) delivered b) can be delivered c) deliver 19. This old car needs ............. a) to fix b) fix c) to be fixed 20. The house has ............. after the fire. a) to rebuild b) to be rebuilt c) rebuilt 21. All the homework ............. at home . a) should be done b) should do c) should be doing 22. The application form ............. to the university before May 31st a) must send b) must be sent c) sent 23. Traffic rules ............. strictly. a) must be followed b) must follow c) followed 24. Students ............. to participate in the after school activities. a) encourage b) are encouraged c) encouraged 25. The performing animals ............. , in iron cages. a) keep b) are keeping c) are kept 26. The animal performance is going to ............. on te1evision tonight. a) show b) be showing c) be shown 27. Water ............. on Mars. " a) might find b) might be found c) is finding 28. The problem of traffic-jam ............. as soon as possible. a) must solve b) must be solved c) must be solving 29. Goods ............. to your house if you order. a) may deliver b) may be delivering c) may be delivered 30. Vietnamese women can continue ............. the unique and fashionable "aodai": a) to wear b) wearing c) wear
Loga.vn - Cộng Đồng Luyện Thi Trực Tuyến