Question

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Answer 1

A ABC dreptunghic
A=90 grade
AB=12
BC=13
AC=?

CB^2= AB^2+AC^2=>13^2=12^2+AC^2
AC^2=13^2-12^2
AC^2=169-144
AC^2=25=>AC= radical din 25=> AC= 5

Answer 2

$\bf \Delta ABC-dreptunghic,\ m(\widehat A)=90^o, AB=12\ cm,\ BC=13\ cm\\ \\ AC=?\ \ \mathcal{A}_{ABC}=?\ \ AD=?\ \ unde\ AD\perp BC$

Rezolvare:

$\it \Delta ABC-dreptunghic,\ m(\widehat A)=90^o,\ \stackrel{TP}{\Longrightarrow}\ AC^2=BC^2-AB^2=13^2-12^2=\\ \\ =169-144=25=5^2 \Rightarrow AC=5\ cm$

$\it \mathcal{A}_{ABC}=\dfrac{c_1\cdot c_2}{2}=\dfrac{AB\cdot AC}{2}=\dfrac{12\cdot5}{2}=\dfrac{60}{2}=30\ cm^2\\ \\ \\ AD=\dfrac{AB\cdot AC}{BC}=\dfrac{12\cdot5}{13}=\dfrac{60}{13}\ cm$