CHo hỏi bài toán trong vòng hôm nay

N

nttthn_97

$\widehat{SAD}=\widehat{SAB}+ \widehat{BAD}$

$\widehat{SDA}=\widehat{DAC}+ \widehat{DCA}$(góc ngoài)

Mà $\widehat{SAB}=\widehat{DCA}$ (chắn cung AB)

$\widehat{BAD}=\widehat{DAC}$

[TEX]\Rightarrow[/TEX]$\widehat{SAD}=\widehat{SDA}$

[TEX]\Rightarrow[/TEX]SAD cân [TEX]\Rightarrow[/TEX]SA=SD
 
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