Trong tứ giác \(ABCD\) ta có: \(\widehat A+\widehat B+\widehat C+\widehat D=360^0\)
\(\Rightarrow \widehat A+\widehat B=360^0-(\widehat C+\widehat D)\)
\(\Rightarrow \widehat A + \widehat B = {360^0} - \left( {{{60}^0} + {{80}^0}} \right) = {220^0}\)
Mà \(\widehat A - \widehat B = {10^0} \)
\(\Rightarrow 2\widehat A =230^0\)\(\Rightarrow \widehat A =115^0\)
\(\widehat B=115^0-10^0=105^0\)
Vậy \(\widehat A = {115^0},\widehat B = {105^0}\)
