Fie triunghiul DEF cu m(D)=90 di DM perpendicular pe EF .
Daca DE=30 cm si EF= 50 cm ,calculati lungimile EF, DF si DM

Facem teorema lui Pitagora in ΔDFE, DF²=50²-30²=2500-900=1600 => DF=√1600= 40 cm
Aria ΔDFE este [tex] \frac{DE x DF}{2} [/tex]=[tex] \frac{30 x 50}{2} [/tex]=750 cm²
Tot aria ΔDFE este [tex] \frac{DM x FE}{2} [/tex] =[tex] \frac{DM x 50}{2} [/tex] => 750=25DM => DM=30 cm
Si EF e 50, ti-l da in cerinta..