Ta có \(\widehat{S}+\widehat{SGQ}+\widehat{Q}=180^0\Rightarrow\widehat{S}+\widehat{Q}=180^0-\widehat{SGQ}\)
Mà \(\widehat{S}-\widehat{Q}=12^0\Rightarrow\left\{{}\begin{matrix}\widehat{S}=\dfrac{180^0-\widehat{SGQ}+12^0}{2}=96^0-\dfrac{\widehat{SGQ}}{2}\\\widehat{Q}=\dfrac{180^0-\widehat{SGQ}-12^0}{2}=84^0-\dfrac{\widehat{SGQ}}{2}\end{matrix}\right.\)
Mà GP là p/g nên \(\widehat{QGP}=\widehat{PGS}=\dfrac{\widehat{SGQ}}{2}\)
\(\Rightarrow\widehat{Q}=84^0-\widehat{QGP}\)
Ta có \(\widehat{GPS}=\widehat{Q}+\widehat{QGP}=84^0-\widehat{QGP}+\widehat{QGP}=84^0\) (tc góc ngoài)