*Xét tam giác ABC ta có:

$\widehat{A}+\widehat{B}+\widehat{C}={{180}^{0}}$ (1)

*Xét tam giác DEC có:

$\widehat{E}+\widehat{EDC}+\widehat{C}={{180}^{0}}$(2)

Mặt khác: $\widehat{A}=\widehat{E}={{90}^{0}}$ (3)

Từ (1); (2); (3) suy ra $\widehat{EDC}=\widehat{B}={{56}^{0}}$

Ta lại có:

$\widehat{EDC}+\widehat{ADE}={{180}^{0}}$

$\Rightarrow \widehat{ADE}={{180}^{0}}-\widehat{EDC}$

$\Rightarrow \widehat{ADE}={{180}^{0}}-{{56}^{0}}={{124}^{0}}$