Răspunsuri

2014-04-28T21:09:28+03:00
BD inaltimea
In tr ABD  daca notam BD=x si AD=y⇒
cu Pitagora
(4√5)²=x²+y²
tg B=y/x=1/2 ,x=2y

din cele 2 avem
80=4y²+y²=5y²
y=√80/√5=4√5/√5=4=AD
x=2y=8=BD 
BC=BD.2=16
 P=4√5+4√5+16=8√5+16

cosB=cateta alaturata/ipotenuza=BD/AB=8/4√5=2√5/5