Giải:
a) Xét \(\Delta ABD,\Delta EBD\) có:
\(AB=BE\left(gt\right)\)
\(\widehat{B_1}=\widehat{B_2}\left(=\frac{1}{2}\widehat{B}\right)\)
\(BD\): cạnh chung
\(\Rightarrow\Delta ABD=\Delta EBD\left(c-g-c\right)\)
\(\Rightarrow DA=DE\) ( cạnh t/ứng )
b) Vì \(\Delta ABD=\Delta EBD\)
\(\Rightarrow\widehat{A}=\widehat{BED}\)
Mà \(\widehat{A}=90^o\Rightarrow\widehat{BED}=90^o\)
Vậy a) DA = DE
b) \(\widehat{BED}=90^o\)
Đúng 7
Bình luận (1)
