\(\widehat{BOI}=\frac{1}{4}\widehat{AOB}=>\widehat{BOI}=\frac{1}{4}\cdot60^O\)\(=>\widehat{BOI}=15^O\)
Vì tia OI nằm giữa hai tia OA và OB
\(=>\widehat{AOI}+\widehat{BOI}=\widehat{AOB}\)
Thay \(\widehat{BOI}=15^o,\widehat{AOB}=60^o\),ta có:
\(\widehat{AOI}+15^o=60^o\)
\(=>\widehat{AOI}=60^o-15^o\)
\(=>\widehat{AOI}=45^o\)
Vậy \(\widehat{BOI}=15^o;\widehat{AOI}=45^o\)