Xét \(\Delta DAB(D_1=90^o)\) có:
\(AD^2+BD^2=AB^2 \) (py_ta_go)
\(\Rightarrow AD^2=AB^2-BD^2=17^2-15^2=64\)
\(\Rightarrow AD=\sqrt{64}=8(cm)\)
Xét \(\Delta DBC(D_2=90^o)\) có:
\(DC=AC-AD=17-8=9(cm)\)
\(BC^2 =BD^2+DC^2\) (py_ta_go)
\(\Rightarrow BC^2=15^2+9^2=306\)
\(\Rightarrow BC=\sqrt{306}=3\sqrt{34}(cm)\)
Chúc bạn học tốt!