Bài 2:
Do \(AH\perp BC=\left\{H\right\}\left(gt\right)\Rightarrow\widehat{AHB}=\widehat{AHC}=90^0\)
+) Trong \(\Delta AHB\) có : \(\widehat{AHB}=90^0\left(cmt\right)\)
\(\Rightarrow AB^2=AH^2+BH^2\) ( định lý Py-ta-go )
\(\Rightarrow AB^2=2^2+1^2\)
\(\Rightarrow AB^2=4+1\)
\(\Rightarrow AB^2=5\)
\(\Rightarrow AB=\sqrt{5}\) ( cm ;AB>0)
+) Trong \(\Delta AHC\) có : \(\widehat{AHC}=90^0\left(cmt\right)\)
\(\Rightarrow AC^2=HC^2+AH^2\) ( định lý Py-ta-go )
\(\Rightarrow AC^2=3^2+2^2\)
\(\Rightarrow AC^2=9+4\)
\(\Rightarrow AC^2=13\)
\(\Rightarrow AC=\sqrt{13}\left(cm;AC>0\right)\)
Chúc bn học tốt!
