Question

Suma tuturor muchiilor unui tetraedru regulat cu aria totala 25√3 cm² este egal cu........cm.

Answer 1

At=l²√3

25√3=l²√3

l²=25√3/√3

l²=25

l=√25

l=5

S=5*6=30

Answer 2

At=Al+Ab

Ab=l²√3/4
Al=Pb*ap/2

ap=l√3/6

At= l²√3/4 + 3l*l√3/6/2

At= l²√3/4  + l²√3/2/2

At=l²√3/4 + l²√3/4

At=2l²√3/4

2l²√3/4=25√3

l²= 25√3*4/2√3

l²= 25*2

l²=50  ⇒l=5√2

S=6*5√2=30√2