Volumes and areas of body surfaces Volumes and areas of body surfaces: prism, parallelepiped, right prism, right-angled parallelepiped, cube, pyramid, regular pyramid, truncated pyramid, regular truncated pyramid, circular cylinder, round cylinder, circular cone, round cone, truncated circular cone, truncated round cone, sphere (ball), hemisphere, spherical … [Read more...]

## Similarity of bodies

Similarity of bodies Similar bodies. Mirror similar bodies. Relations of corresponding sizes in similar figures and bodies. Two bodies are similar, if one of them can be received from another by increasing (or decreasing) of all its linear dimensions by the same ratio. A car and its model are similar bodies. Two bodies (or figures) are mirror similar, if one of them … [Read more...]

## Symmetry. Symmetry of plane figures

Symmetry. Symmetry of plane figures Mirror symmetry. Symmetry plane. Symmetrical figures. Mirror equal figures. Central symmetry. Symmetry center. Rotation symmetry. Symmetry axis. Axial symmetry. Examples of a symmetry kinds. Symmetry of plane figures. Examples of symmetry of plane figures. Mirror symmetry. A geometric figure is called a symmetrical relatively a … [Read more...]

## Regular polyhedrons

Regular polyhedrons Regular polygons. Convex regular polyhedrons: tetrahedron, hexahedron (cube), octahedron, dodecahedron, icosahedron. Non-convex regular polyhedrons. A polyhedron is called a regular one, if all its faces are equal regular polygons and the same number of faces join in each its vertex. It is known only five convex regular polyhedrons and four … [Read more...]

## Solid angles

Solid angles Solid angle. Measure of a solid angle. Steradian. A solid angle is a part of a space, concluded inside of one part of a conic surface with a closed directrix. A solid angle is measured by a piece of spherical surface ( ABCDEF, Fig.98 ). A measure of a solid angle is a ratio of an area ABCDEF to a square of radius of the ball: A measure unit of a … [Read more...]