[latexpage]

**Cuboid**: A solid whose, length, breadth & height are different is called a cuboid. It has a six rectangular plane faces, 12 edges & 8 vertex.

**Cube**: A cuboid whose length ,breadth & height are equal is called a cube.

**Cylinder**: When a rectangle. OABO’ is rotate at its oo’ axis in initial position to $360^0$ thus form a solid is called cylinder .

**Cone**: When a triangle AOV is rotate to its OV axis in initial position to $360^0$ thus form a solid is called cone.

**Prism**: When a traingle raise a required height H thus form a solid is called prism.

Cubes and cuboids are also known as square prism and rectangle prism.

**Sphere**: When a circle is rotate at its AOB axis in initial position to $360^0$ thus form a solid is called sphere.

**Pyramid**:A solid whose base is triangle or square in shape & it’s all vertices are meet a point at height H.

**Triangular pyramid**: A pyramid having triangular base is called triangular pyramid. He is also called a tetrahedeon (four faced sided )

**Square pyramid**: A pyramid having a square base is called a square pyramid.

**Continued proportion** e.g. 4:3::8:16

**Mean proportion** e.g. 4:2::8:16 or 82 = 4×16

8 is mean proportion.

**Third proportion** 4:8::8:16 – 16 is called third proportion.

**Unitary method** The method of finding is the value of one unit from the values of given own.