Răspuns :
VABC-piramida patrulatera regulata
VA=VB=VC=VD
mas<(VA;BC)=mas<(VB;BC)=mas<(VBC)=60 grade
VA=VB=VC=VD
mas<(VA;BC)=mas<(VB;BC)=mas<(VBC)=60 grade
BC || AD
⇒m(VA,BC)=m(VA,AD)=m(VAD)
ΔVAD ECHILATERAL
⇒m(VAD)=180:3=60