\(\widehat{BOI}=\frac{1}{4}\widehat{AOB}\Rightarrow\widehat{BOI}=\frac{1}{4}.60^o\Rightarrow\widehat{BOI}=15^o\)
Vì tia OI nằm giữa hai tia OA và OB
\(\Rightarrow\widehat{AOI}+\widehat{BOI}=\widehat{AOB}\)
Thay \(\widehat{BOI}=15^o,\widehat{AOB}=60^o\), ta có:
\(\widehat{AOI}+15^o=60^o\)
\(\Rightarrow\widehat{AOI}=60^o-15^o\)
\(\Rightarrow\widehat{AOI}=45^o\)
Vậy \(\widehat{BOI}=15^o,\widehat{AOI}=45^o\)