a ) Vì \(xOt\) và \(yOz\) cùng kề phụ với \(zOt\)
\(\Rightarrow xOt=yOz\)
b ) Ta có :
\(xOz+yOt=180\)
\(\Rightarrow xOy+zOt=180\) ( đpcm )
Bạn tự vẽ hình nhé!
a) Ta có: \(\widehat{xOt}+\widehat{tOz}=\widehat{xOz}\)
\(\Rightarrow\widehat{xOt}+\widehat{tOz}=90^o\)
\(\widehat{yOz}+\widehat{tOz}=\widehat{yOt}\) \(\Rightarrow\widehat{yOz}+\widehat{tOz}=90^o\)
Khi đó: \(\widehat{xOt}+\widehat{tOz}=\widehat{yOz}+\widehat{tOz}\)
\(\Rightarrow\widehat{xOt}=\widehat{yOz}\)
b) Lại có: \(\widehat{xOy}=\widehat{xOz}+\widehat{yOz}\)
=\(\widehat{xOt}+\widehat{tOz}+\widehat{yOz}\)
\(=90^o-\widehat{tOz}+\widehat{tOz}+90^o-\widehat{tOz}\)
\(=180^o-\widehat{tOz}\)
\(\Rightarrow\widehat{xOy}+\widehat{tOz}=180^o\) (chuyển vế) \(\rightarrowđpcm.\)
