Din ΔADC,cu∡ ADC=90
sin C= 0,8=8/10=4/5=AD/AC
4/5=60/AC
AC=75 cm
cu Pitaagora avem
DC²=AC²-AD²=75²-60²=5625-3600=2025
DC=45 cm
Teorema inaltimii
AD²=BD.DC
60²=BD.45
BD=3600/45=80 cm
in ΔADB cu AD⊥BC
AB²=BD²+AD²=6400+3600=10000
AB=100 cm
P(ABC)=AB+BC+CA=100+125+75=300 cm
