Traditional Culture Encyclopedia - Photography and portraiture - In the triangular pyramid P-ABC, the photography of the vertex P in the plane ABC is the outer center of the triangular line ABC, and it is proved that PA=PB=PC.

In the triangular pyramid P-ABC, the photography of the vertex P in the plane ABC is the outer center of the triangular line ABC, and it is proved that PA=PB=PC.

Let the projection of p on the plane ABC be o, then the PO⊥ plane ABC,

O is the outer center of the triangle,

Then AO=BO=CO,

< poa = < pob = POC = 90 degrees,

PO=PO=PO (common side),

RT△PAO≌RT△PBO≌RT△PCO，

∴PA=PB=PC。