a) Vì \(\widehat{yOt}=\widehat{xOz}\left(=90^o\right)\)
nên \(\widehat{xOy}+\widehat{xOt}=\widehat{zOt}+\widehat{xOt}\)
Vậy \(\widehat{xOy}=\widehat{zOt}\)
b) Ta có:
\(\widehat{zOy}+\widehat{tOx}=\widehat{xOy}+\widehat{zOt}+\widehat{tOx}+\widehat{tOx}\\ =2\left(\widehat{xOy}+\widehat{tOx}\right)=2\widehat{yOt}=2.90^o=180^o\)
Vậy \(\widehat{zOy}+\widehat{tOx}=180^o\)