Đáp án:
$\widehat{xOy}$ `=` $\widehat{x'Oy'}$ `=` $60^{o}$ ; $\widehat{xOy'}$ `=` $\widehat{x'Oy}$ `=` $120^{o}$
Giải thích các bước giải:
Ta có : $\widehat{xOy'}$ `+` $\widehat{xOy}$ `=` $180^{o}$ ( Hai góc kề bù )
Mà $\widehat{xOy'}$ `-` $\widehat{xOy}$ `=` $60^{o}$ ( Theo đề bài )
`=>` Cộng vế với vế , ta được :
$\widehat{xOy'}$ `+` $\widehat{xOy}$ `+` $\widehat{xOy'}$ `-` $\widehat{xOy}$ `=` $240^{o}$
`2 .` $\widehat{xOy'}$ `=` $240^{o}$
`=>` $\widehat{xOy'}$ `=` $120^{o}$
`=>` $\widehat{xOy}$ `=` $180^{o}$ `-` $120^{o}$ `=` $60^{o}$
Ta thấy :
`+` $\widehat{xOy}$ `=` $\widehat{x'Oy'}$ `=` $60^{o}$ ( Hai góc đối đỉnh )
`+` $\widehat{xOy'}$ `=` $\widehat{x'Oy}$ `=` $120^{o}$ ( Hai góc đối đỉnh )
Vậy $\widehat{xOy}$ `=` $\widehat{x'Oy'}$ `=` $60^{o}$ ; $\widehat{xOy'}$ `=` $\widehat{x'Oy}$ `=` $120^{o}$
