giúp mình với !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Ta có: `a` `/``/ b`

`=>` $\widehat{D_{1}}$ = $\widehat{DAB}$ ( `2` góc đồng vị )

mà $\widehat{DAB}$ `= 90^o`

`=>` $\widehat{D_{1}}$ `= 90^o`

Ta có: `a` `/``/ b`

`=>` $\widehat{DCB}$ `=` $\widehat{B_{1}}$ ( `2` góc so le trong )

mà $\widehat{DCB}$ `= 130^o`

`=>` $\widehat{B_{1}}$ `= 130^o`

$#Nhi$