Răspunsuri

2014-03-06T17:23:19+02:00
Ce clasa? e important

Daca ai facut teorema lui Pitagora si tangenta:

AB²=AD²+BD², AB=15; TG(BAC)=TG(BAD), BC/AB=BD/AD, BC= AB*BD/AD= 20; AC²=AB²+BC²; AC=25; P (ABC)=60



Atunci:
TEOREMA INALTIMII: BD²=AD*DC⇒ 144=9*DC⇒DC=16⇒ AC=25
TEOREMA CATETEI: AB²=AD*AC⇒AB²=225⇒AB=15
TEOREMA CATETEI: BC²=CD*AC⇒ BC²=400⇒BC=20
AB²=AD*AC
AB^2=AD^2+BD^2, AB=15; TG(BAC)=TG(BAD), BC/AB=BD/AD, BC= AB*BD/AD= 20; AC^2=AB^2+BC^2; AC=25; P (ABC)=60
2014-03-06T17:42:19+02:00
Din T.P. aplicata in ΔABD ⇒ AB²=BD²+AD²
AB²=12²+9²
AB=√225=15 cm 
sin C= AB/BC
sin C =1/2 ⇒ AB/BC=1/2
15/BC=1/2⇔ BC=15/2=7,5 cm
AC²=AB²+BC²
AC²=15²+7,5²
AC=√281.25≈16,77
P= AB+AC+BC
P=15+7,5+16,77=39,27

Aha, eu sunt in a 8a si asa o fac. In fine
Atunci:
TEOREMA INALTIMII: BD²=AD*DC⇒ 144=9*DC⇒DC=16⇒ AC=25
TEOREMA CATETEI: AB²=AD*AC⇒AB²=225⇒AB=15
TEOREMA CATETEI: BC²=CD*AC⇒ BC²=400⇒BC=20
AB²=AD*AC
VEZI CA NU APLICAI BINE TEOREMA CATETEI :BC²=CD*AC (UNGHIUL B ARE 90 GRD)
IPOTENUZA ESTE AC
multumesc foarte mult, am refacut si eu problema folosind cele doua teoreme.