b) In triunghiul ABD (<D=90grade), AB=30cm, BD=18cm
cf.th.Pitagora aflam AD = 24cma) In triunghiul ABC, AD = inaltimecf.th.inaltimii AD2=BDxDCinlocuim 576 = 18xDCDC = 32cmBC= BD+DC =18+32= 50cmc)in triunghiul ABC , cf.th.Pitagora aflam AC=40cmcos (DAC)= 24/40=3/5