Vì Om là tia phân giác \(\widehat{xOy}\)=>\(\widehat{xOm}=\widehat{mOy}=\frac{\widehat{xOy}}{2}\)
On là tia phân giác \(\widehat{yOz}\)=>\(\widehat{yOn}=\widehat{nOz}=\frac{\widehat{yOz}}{2}\)\(\)
Ta có:\(\widehat{mOy}+\widehat{yOn}=\frac{\widehat{xOy}}{2}+\frac{\widehat{yOz}}{2}\)=\(\frac{\widehat{xOy}+\widehat{yOz}}{2}\)\(=\frac{180độ}{2}=90độ\)
=>\(\widehat{mOn}=90độ\)
Vì \(AB⊥Om\) ;\(CO⊥Om\)
=>AB//CO=>\(\widehat{CAB}+\widehat{ACO}=180độ\)(hai góc trong cùng phía bù nhau)
\(\widehat{CAB}+90độ=180độ\)
\(\widehat{CAB}=90độ\)