a)sinB=AC/BC => AC/BC=12/13 => AC=12xBC/13=12cm
din Pitagora calc.AB^2=BC^2-AC^2 (^2==puterea a doua)
AB^2=169-144=25 => AB=5cm
tgC=AB/AC=5/12
b)din Pitagora BC^2=AB^2+AC^2=9+27=36 => BC=6cm si sinB=AC/BC=3V3/6=V3/2
c)sinC=AB/BC=3/5 => (AB+BC)/BC=(3+5)/5 => 24/BC=8/5 => BC=24x5/8=15cm
=> AB=24-15=9cm si din Pitagora AC^2=BC^2-AB^2=225-81=144 deci AC=12cm