Illustration of 4 congruent rectangular prisms placed in the shape of a square. They are arranged to…

Diagram used to prove the theorem: "Two prisms are equal when the three faces about a trihedral of one…

Illustration used to show that two triangles are equal if the three sides of one are equal respectively…

Diagram used to prove the theorem: "The plane passed through two diagonally opposite edges of a parallelopiped…