A cylinder.
A four faced figure is a tetrahedron. If they are all congruent triangles, they are all equilateral triangles and it is a regular tetrahedron - one of the 5 Platonic Solids.
In gemortry, CPCTC is the abbreviation of a therom involving congrugent triangles. CPCTC stands for Corresponding Parts of Congruent Triangles are Congruent. CPCTC states that if two or more triangles are proven congruent by: ASA, AAS, SSS, HL, or SAS, then all of their corresponding parts are congruent as well.Ifthen the following conditions are true:A related theorem is CPCFC, in which triangles is replaced with figures so that the theorem applies to any polygon or polyhedrogen.