Đáp án:
a. \(\widehat{aOb}=60°\)
Các bước giải:
a. Ta có:
\(\widehat{xOb}\) = 120 \(^{\circ}\)
\(\widehat{xOa}\) = 60 \(^{\circ}\)
Suy ra: \(\widehat{xOb}\) > \(\widehat{xOa}\) ( 120 \(^{\circ}\) > 60 \(^{\circ}\))
Tia Oa nằm giữa hai tia Ox và Ob
\(\widehat{aOb}\) = \(\widehat{xOb}\) - \(\widehat{xOa}\) = 120 \(^{\circ}\) - 60 \(^{\circ}\) = 60\(^{\circ}\)
b. Ta có:
\(\widehat{xOb}+\widehat{bOy}=180°\)
\(\widehat{aOt}=\widehat{aOb}+\widehat{bOt}=\frac{1}{2}.\widehat{xOb}+\frac{1}{2}.\widehat{bOy}=\frac{1}{2}(\widehat{xOb}+\widehat{bOy})=\frac{1}{2}.180°=90°\) (\(\widehat{aOb}=\frac{1}{2}\widehat{xOb}; \widehat{bOt}=\frac{1}{2}.\widehat{bOy}\) do Oa tia phân giác \(\widehat{xOb}\); Ot là tia phân giác \(\widehat{bOy}\))