giúp a b với ạ kakqkqkqkwkkk

`1)`

`a)` Xét $\triangle$ `AHF,` $\triangle$ `CHD` có:

$\widehat{AFH}$ `=` $\widehat{HDC}$ `

`(=90^0)`

$\widehat{AFH}$ `=` $\widehat{CHD}$ (đối đỉnh)

`->` $\triangle$ `HAF` $\backsim$ $\triangle$ `HCD (g.g)`

`-> HA/HC = HF/HD`

`-> HA. HD = HF. HC`

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`b)` Xét $\triangle$ `CEH,` $\triangle$ `BEA` có:

$\widehat{CEH}$ `=` $\widehat{AEB}$ `(=90^0)`

$\widehat{ECH}$ `= 90^0 -` $\widehat{EHC}$ `= 90^0 -` $\widehat{FHB}$ `=` $\widehat{HBG}$ `=` $\widehat{ABE}$

`->` $\triangle$ `CEH` $\backsim$ $\triangle$ `BEA (g.g)`

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`c)` đề sai nhé.