Đáp án:
$x$ $=$ $100°$ ; $y$ $=$ $140°$
Giải thích các bước giải:
Hình thang $ABCD$ ( $AB$ $//$ $CD$ ), có:
$\widehat{A}$ + $\widehat{D}$ $=$ $180°$ ( 2 góc kề cạnh bên )
$\widehat{A}$ + $80°$ $=$ $180°$
$⇒$ $\widehat{A}$ $=$ $180°$ - $80°$ $=$ $100°$.
Vậy $x$ $=$ $100°$.
Ta có: $\widehat{B}$ + $\widehat{C}$ $=$ $180°$ ( 2 góc kề cạnh bên )
$40°$ + $\widehat{C}$ $=$ $180°$
$⇒$ $\widehat{C}$ $=$ $180°$ - $40°$ $=$ $140°$.
Vậy $y$ $=$ $140°$.
$#Tuantuth23$
$@Shun$ - $@Aqua$~
