Mng làm giúp mik vs. Thanks

$\text{Xét }$$\Delta$ $\text{vuông}$ `ABC:` $\widehat{BCA}$ `=` $90^{o}$ `-` $\widehat{ABC}$ `=` $90^{o}$ `-` $41^{o}$ `=` $49^{o}$

$\text{Xét }$$\Delta$ $\text{vuông}$ `DEC:` $\widehat{ECD}$ `=` $90^{o}$ `-` $\widehat{DEC}$ `=` $90^{o}$ `-` $49^{o}$ `=` $41^{o}$

$\text{Ta có: }$$\widehat{BCA}$ `+` $\widehat{ECD}$ `+` $\widehat{BCE}$ `=` $180^{o}$

`⇒` $49^{o}$ `+` $41^{o}$ `+` $\widehat{BCE}$ `=` $180^{o}$ `⇒` $90^{o}$ `+` $\widehat{BCE}$ `=` $180^{o}$

`⇒` $\widehat{BCE}$ `=` $90^{o}$ `⇒` `BC` $\bot$ `CE`

$\textit{#TranDucQuangNBK}$