Cho nửa đường tròn tâm O đường AB.Trên nửa đường tròn lấy 2 điểm C và D.Qua B kẻ đường thẳng a vuông góc với AB.Các tia AC,AD lần lượt cắt đường thẳng a tại E và F.

a)CMR:AC.AE=AD.AF

b)Tìm vị trí điểm C để tổng s=2AC+AE đạt min

Cho hàm số y=mx-m+1(d_m)với m là tham số

a)Vẽ đồ thị của hàm số khi m=1

b)CMR:Các đường thẳng d_m luôn luôn đi qua 1 điểm cố định trong mặt phẳng tọa độ với mọi giá trị của m

c)Tìm giá trị của m để khoảng cách từ O đến đường thẳng d_m lớn nhất

Cho tam giác ABC.Kẻ 3 đường cao AH,BK và CE.CMR:

\(a)\frac{AK^2}{AB^2}=\frac{AE.KE}{AC.BC}\\ b)\frac{S_{AKE}}{S_{ABC}}=Cos^2A\\ c)\frac{S_{MKE}}{S_{ABC}}=1-\left(Cos^2A+Cos^2B+Cos^2C\right)\)

Cho tam giác ABC vuông tại A,AB=m,góc ABC=60^o

a)Tính AB,BC theo m

b)Kẻ phân giác BD của góc ABC.Tính DA,AB theo m.Kiểm nghiệm rằng\(\frac{DA}{DC}=\frac{AB}{AC}\)

The general opinion abroad is that London has fog or rain or both every day of the.

year, but on the day I arrived it was fine and warm, there was a bright sun and a cloudless sky.The next day it was just as beautiful, there was a slight wind that.

gently moved the leaves on the trees ,and you could smell the spring in the air.

''Life is grand'' I thought as I walked in Kensington gardens .It was a straight road

and I fond the way quite easily. When I got my first sight of the gardens the beauty of it nearby took my breath away. The trees were just bursting into leaf, fresh and green and lovely, and were beds of spring flowers, red and yellow and blue, in the beautiful, smooth grass under the trees.

People in light spring clothes were walking about, and to my surprise, they walked not only along to the paths but also across the grass, and no one said a work to them about it. I had never seen such a thing before.

1.Which season was it when he visited London?

2.What was the strange thing in Kensington Gardens that he saw?

Who draw...........................Nam,Lan or Quang?(good)

John has never eaten with chopsticks

If you want.........................................................

Don't worry .We can help you to improve your English.

If you want .............................................

"Why don't we make a big cake for Lan's birthday?"he asked .

He suggested .........................................

Làm thế nào để có thể nhận, đọc và gửi thư khi có hộp thư điện tử?