Question

Fie VABC o piramida triunghiulara regulata cu varful in V care are perimetrul bazei de 48 cm si permetrul unei fete laterale de 36 cm.Aflati:
a) l;
b) m;
c)A bazei;
d)A fetei;

Answer 1

Pb=3l=>l=Pb/3=48/3=16 cm

Pf=2m+l=>2m=Pf-l=>m=(Pf-l)/2=(36-16)/2=20/2=10 cm

Ab=l²√3/4=16²√3/4=256√3/4=64cm²

Af=ap*l/2

ap->apotema piramidei

ap²=m²-(l/2)²=10²-(16/2)²=100-64=36=>ap=√36=6 cm

Af=6*16/2=6*8=48 cm²