Platonic solids

"In Euclidean geometry, a Platonic solid is a regular, convex polyhedron with congruent faces of regular polygons and the same number of faces meeting at each vertex. Five solids meet those criteria, and each is named after its number of faces.
Geometers have studied the mathematical beauty and symmetry of the Platonic solids for thousands of years. They are named for the ancient Greek philosopher Plato who theorized in his dialogue, the Timaeus, that the classical elements were made of these regular solids." [Platonic solid. Wikipedia]
The geometry diagram example "Platonic solid" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Mathematics solution from the Science and Education area of ConceptDraw Solution Park.

The vector stencils library "Solid geometry" contains 15 shapes of solid geometric figures.
"In mathematics, solid geometry was the traditional name for the geometry of three-dimensional Euclidean space - for practical purposes the kind of space we live in. It was developed following the development of plane geometry. Stereometry deals with the measurements of volumes of various solid figures including cylinder, circular cone, truncated cone, sphere, and prisms.
The Pythagoreans had dealt with the regular solids, but the pyramid, prism, cone and cylinder were not studied until the Platonists. Eudoxus established their measurement, proving the pyramid and cone to have one-third the volume of a prism and cylinder on the same base and of the same height, and was probably the discoverer of a proof that the volume of a sphere is proportional to the cube of its radius." [Solid geometry. Wikipedia]
The shapes example "Design elements - Solid geometry" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Mathematics solution from the Science and Education area of ConceptDraw Solution Park.

This chemical laboratory technique drawing depict gravity filtration of liquid through prepleated paper filter step-by-step.
1. Put folded filter paper cone into glass filter funnel inserted into neck of conical (Erlenmeyer) flask.
2. Add liquid suspension from the glass beaker with a spout into the funnel with paper filter.
3. Collect filtrate in the conical flask and solid on the paper filter in the funnel.
"Filtration is commonly the mechanical or physical operation which is used for the separation of solids from fluids (liquids or gases) by interposing a medium through which only the fluid can pass. The fluid that pass through is called a filtrate. Oversize solids in the fluid are retained, but the separation is not complete; solids will be contaminated with some fluid and filtrate will contain fine particles (depending on the pore size and filter thickness)." [Filtration. Wikipedia]
"Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solids from liquids or air." [Filter paper. Wikipedia]
The chemical lab drawing example "Gravity filtration of liquids" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Chemistry solution from the Science and Education area of ConceptDraw Solution Park.