Giải giúp mik vs ạ. Hạn nộp là trc 12h ạ, c onn mn nhìu

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Bài `2:`

`a)`

$\widehat{A_1}$ `+` $\widehat{A_2}$ `= 180^o` `(` kề bù `)`

`<=>` $\widehat{50^o}$ `+` $\widehat{A_2}$ `= 180^o`

`<=>` $\widehat{A_2}$ `= 130^o`

Mà $\widehat{A_2}$ `+` $\widehat{A_3}$ `= 180^o` `(` kề bù `)`

`<=>` $\widehat{A_3}$ `= 180^o - 130^o = 50^o`

`b)`

$\widehat{B_1}$ `+` $\widehat{B_2}$ `= 180^o` `(` kề bù `)`

`<=>` $\widehat{123^o}$ `+` $\widehat{B_2}$ `= 180^o`

`<=>` $\widehat{B_2}$ `= 57^o`

Mà $\widehat{B_2}$ `+` $\widehat{B_3}$ `= 180^o` `(` kề bù `)`

`<=>` $\widehat{B_3}$ `= 180^o - 57^o = 123^o`