Triunghiul ABC
m (A)=90°
AB=9 cm
AC=12 cm
AD perpendicular BC
-----------------------------
AD=?
BC=?
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ABC. ========>
m(A)=90°========>. BC^2=AC^2+AB^2
BC^2=81+144
BC=√225==>BC=25
ABC. =========>
m(A)=90°=========> AD= (AB*AC)\BC
AD=(9*12)\25==>AD=4.32 cm