Question

Answer 1

Xét \(\Delta ABC\) vuông tại B:

\(AC^2=AB^2+BC^2\left(Pytago\right).\\ \Rightarrow6,5^2=AB^2+2,5^2.\\ \Rightarrow AB^2=6,5^2-2,5^2=36.\\ \Rightarrow AB=6\left(m\right).\)

Answer 2

 help vs dag can gap

 

 

Answer 3

\(\text{Xét }\Delta ABC\text{ vuông tại B có:}\)

\(AC^2=CB^2+AB^2\)

\(\Rightarrow AB^2=AC^2-CB^2\text{(định lí Py ta go đảo)}\)

\(\Rightarrow AB^2=6,5^2-2,5^2=42,25-6,25=36\left(cm\right)\)

\(\Rightarrow AB=\sqrt{36\left(cm\right)}=6\left(cm\right)\)