Hình khó nghen

T

thotim

B

billy9797

gọi CG là đường cao [tex]\large\Delta[/tex]HDG
ta có:[TEX]\frac{S_(AHF)}{S_(AHD)}=\frac{AF}{AD} , \frac{S_(AHD)}{S_(HDG)}=\frac{AH}{CG}[/TEX]
[TEX]\Rightarrow \frac{AD.CG}{AF.AH}=\frac{S_(CDH)}{S_(AFH)}=9[/TEX]
[TEX]\Rightarrow \frac{CD.CG}{AE.AH}=9[/TEX]
c/m dc [tex]\large\Delta[/tex]AEH đồng dạng [tex]\large\Delta[/tex]CDG
[TEX]\Rightarrow(\frac{CD}{AE})^2=\frac{CD.CG}{AE.AH}=9[/TEX]
[TEX]\Rightarrow AD=3AE[/TEX]
đánh mấy cái công thức này mệt quá
 
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