cho tam giác ABC vuông tại A có AH đg cao, HD ⊥ AB, HE ⊥ AC.

a)C/m: ΔADE∼ΔACB

b) gọi M, N trung điểm BH, CH. Tính S\(_{MNED}\) biết S\(_{ABC}\) = 60 cm^2

charles_______ his father in the shop until shool_______

A. was helping-will start         B. helped- was starting          C. is helping- starts     D.has helped-is starting

cho tam giác ABC nhọn, có BD đg cao, CE đg cao, 2 đg cao cắt nhau tại H

c/m: BH.BD + CH.CE = BC^2

the heads of four America presidents are...........into the rock at Mount Rushmore

A.carved         B.built        C.painted        D. seen

we play sports regulary........have good health

A.in order that      B.in order to       C.so as           D.so as not to

He asked me...........a driving licence

A. if I have           B. whether I have          C.if I had         D. whether I have had

Nga advised Nhi how(go)........from My Son to Hoi An

1.could you wait a moment, please?

-> do you mind.........................?

2.his father will repair his bicycle tomorrow

-> his bicycle.................

3. "are you free tonight?", my mother said to me

->my mother asked...................

1.could you wait a moment, please?

-> do you mind.........................?

2.his father will repair his bicycle tomorrow

-> his bicycle.................

3. "are you free tonight?", my mother said to me

->my mother asked...................

giải pt:

|-3x|=2x-1