Răspuns :

AB²=BD*BC
BC=BD+DC=9+16=25
AB²=9*25
AB=√9*25=3*5=15
aplic teorema inaltimii in trg ABC ⇒ AD^2=BD*CD=16*9=144 ⇒ AD=12 cm
Aplic T Pitagora in trg ABD si am
AB^2=AD^2+BD^2=144+81=225 cm^2 ⇒ AB=15 cm