a: \(\widehat{B}=\widehat{Q}=55^0\)
=>\(\widehat{A}+\widehat{C}=180^0-55^0=125^0\)
\(3\cdot\widehat{A}=2\cdot\widehat{C}\)
nên \(\widehat{A}=\dfrac{2}{3}\cdot\widehat{C}\)
\(\widehat{A}=125^0\cdot\dfrac{2}{5}=50^0=\widehat{P}\)
\(\widehat{C}=125^0-50^0=75^0=\widehat{R}\)
b: AC=RT=35cm
ST=10+RT=45(cm)=BC
3BC=5AB
nên 5AB=3BC
=>AB=3/5BC=27(cm)
=>RS=27(cm)