ADB triunghi dreptunghic
tgB=AD/BD, AD=BDtgB=9x2/3=6
t lui Pitagora
AB²=BD²+AD²=81+36=117, AB=3√13
ABC triunghi dreptunghic, t inaltimii
AD²=BDxDC, DC=AD²/BD=36/9=4
BC=BD+DC=9+4=13
ADB t dreptunghic
t lui Pitagora
AC²=AD²+DC²=36+16=52, AC=2√13
b. sin C=AD/AC=6/2√13=3√13/13
cosC=DC/AC=4/2√13=2√13/13
sinC+cosC=5√13/13