Question

Exercitiul 17/19/20/21

Answer 1

formule tetraedru regulat
l=latura tetraedrului
h=l√6/3
Atotala=4l²√3/4=l²√3
V= l³√2/12

17.  AB=l=10 cm
Atotala=10²√3=100√3 cm²

19.Atotala=108√3 =l²√3
a) l=√(108√3/√3)=√108=6√3 cm²
b)V= (6√3)³√2/12=648√6/12=54√6 cm³

20) V=27√3 cm³ =l³√2/12
l³=27√3/(√2/12) =27×12×√3/√2=27×12×√6/2=27×6√6=
l=3√6 cm
Atotala=(3√6)²√3=54√3 cm²

21.V=18√2 cm³ =l³√2/12
l³=18√2/(√2/12)=18√2×12/√2=18×12=216
l=6

A=6²√3=36√3 cm²