<tớ viết tắt chữ căn là C nhé>Gọi độ dài cạnh tam giác đó là a. Hạ đừ cao Ah, Do là tam giác đề nên cx là trung tuyến nên có BH=1/2a. theo pytago, có a^2 - (a^2)/4=AH^2,=>3/4(a^2)=AH^2, => AH= (C3/2)a. khi đó diện tích abc là (Ah.BC)/2= <(C3/2)a*a>/2=(C3*a^2)/4=(9*C3)/4(theo giả thiết). gộp lại =>a^2=9+a=3=> đg trung bình bằng nửa canh hay bằng nửa a và bằng 1.5

Nếu thêm chữ số 0 vào bên phải số bé ta được số lớn, vậy số lớn gấp 10 lần số bé. 

Số bé là: 374 : (10 + 1) = 34

Số lớn là: 34 x 10 = 340

                        Đ/S: số bé: 34, số lớn: 340

Có diện tích tam giác AMN bằng 3/8 Diện thích ABCD

13.5

Sục H₂S đến dư qua dung dịch chứa AlCl₃, NH₄Cl, NaCl, CuCl₂ cho đến khi bão hoà thu được kết tủa gồm:

A. Cu(OH)_2, Al(OH)₃      

B. CuS và Al₂S₃    

C. Al₂S₃                 

D. CuS 

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