An object which has only height and length are called 2-dimensional figures while an abject which has height length and width are called 3-dimensional object.

**Examples of 2-D figures:**

- Line

- Triangle

- Quadrilateral

- Circle

**Examples of 3-dimensional figures:**

**Cube:**

- In a cube length breadth and height are all equal.

length = breadth = height

- let’s length, breadth and height as a.

It has 6 square face each with side length a.

Volume of cube = a * a * a Volume of cube = a^{3}Surface area of cube = 6 * area of one face Surface area of cube = 6 * a^{2}

**Cuboid:**

- In a cuboid length breadth and height are not equal.

It has 6 square face,

Volume of cuboid = length * breadth * height Surface area of cuboid = 6 * area of one face Surface area of cuboid = length * breadth + length * breadth + breadth * height + breadth * height + length * height + length * height Surface area of cuboid = 2(length * breadth + breadth * height + length * height )

**Sphere:**

- A sphere has radius, volume and surface area:

Volume of sphere = (4 / 3) * Ï€ * radius * radius * radius Volume of sphere = (4 / 3) * Ï€ * r^{3}Surface area of sphere = 4 * &pi * radius * radius Surface area of sphere = 4 * &pi * radius^{2}Volume of hemisphere = (2 / 3) * Ï€ * radius * radius * radius Surface area of sphere = 2 * &pi * radius * radius

**Cylinder:**

- A cylinder is a solid or hollow circular shape object with two circular base.

Volume of cylinder = Ï€ * radius * radius * h Curved surface area of cylinder = 2 * Ï€ * radius * h Total surface area = 2 * Ï€ * radius * h + 2 * &pi * radius * radius

**Cone:**

- A cylinder is a solid or hollow with one circular base and which tappers from base to a point.

Volume of a cone = (1 / 3)Ï€ * radius * radius * height Curved surface area of a cone = Ï€ * radius * slant height Total surface area of cone = Ï€ * radius * slant height + Ï€ * radius * radius

**Pyramid:**

- Pyramid is 3-d object with polygon base, this polygon base is connected to an apex in pyramid.

Volume of a pyramid = (area of base * height) / 3

**Examples:**

- What will be the curved surface area of a cylinder having radius 5cm and height 10cm?

Curved surface area of a cylinder = 2 * Ï€ * r * height = 2 * 22 / 7 * 5 * 10 = 314.285714286 cm^{2}

- What will be the slant height of a cone which have curved surface area 990 cm
^{2}and radius 5 cm?

Curved surface area of a cone = Ï€ * radius * slant height Ï€ * radius * slant height = (22 / 7) * 5 * l l = 63cm

- What is the volume of a square base pyramid having base side 4 cm and height 6cm?

Volume of a square = area of base * height / 3 = 4^{2}* 6 / 3 = 16 * 6 / 3 = 32 cm^{3}

- What will be the volume of a sphere having radius 2.1cm

Volume of a sphere = 4 * Ï€ * radius^{3}/ 3 = (4 / 3) * (22 / 7) * 2.1^{3}= 38.808 cm^{3}

- What will be the surface area of a cube having side length breadth and height 8 cm?

Surface area of a cube = 6 * side^{2}= 6 * 8^{2}= 6 * 64 = 384 cm^{2}