Cho

Câu hỏi: Cho $\widehat{xOy}={120}^o$. Vẽ $Ox\text{'}\perp Ox; Oy\text{'}\perp Oy$ sao cho tia Ox',Oy' nằm giữa hai tia Ox, Oy

A. $\widehat{xOy\text{'}}=\widehat{x\text{'}Oy}$ = $30°$

B. $\widehat{xOy\text{'}}=\widehat{x\text{'}Oy}$ = $45°$

C. $\widehat{xOy\text{'}}=\widehat{x\text{'}Oy}$ = $40°$

D. $\widehat{xOy\text{'}}=\widehat{x\text{'}Oy}$ = $60°$