Mensuration is a subject of geometry. Mensuration deals with the size, region and density of different forms both 2D and 3D. Now, in the introduction to Mensuration, let’s think about 2D and 3D forms and the distinction between them.

A 2D diagram is a shape laid down on a plane by three or more straight lines or a closed segment. Such forms do not have width or height; they have two dimensions-length and breadth and are therefore called 2D shapes or figures. Of 2D forms, area (A) and perimeter (P) is to be determined.

A 3D shape is a structure surrounded by a variety of surfaces or planes. These are also considered robust types. Unlike 2D shapes, these shapes have height or depth; they have three-dimensional length, breadth and height/depth and are thus called 3D figures. 3D shapes are actually made up of a number of 2D shapes. Often known as strong forms, volume (V), curved surface area (CSA), lateral surface area (LSA) and complete surface area (TSA) are measured for 3D shapes.

Until we switch to the list of important formulas for measurement, we need to clarify certain important terms that make these formulas for measurement:

The area is called the surface occupied by a defined closed region. It is defined by the letter A and expressed in a square unit.

The total length of the boundary of a figure is called its perimeter. Perimeter is determined of only two-dimensional shapes or figures. It is the continuous line along the edge of the closed vessel. It is represented by P and measures are taken in a square unit.

The width of the space contained in a three-dimensional closed shape or surface, such that, the area by a room or cylinder. Volume is denoted by the alphabet V and the SI unit of volume is the cubic meter.

The curved surface area is the area of the only curved surface, ignoring the base and the top such as a sphere or a circle. The abbreviation for the curved surface area is CSA.

The total area of all of a given figure’s lateral surfaces is called the Lateral Surface Area. Lateral surfaces are the layers covering the artefact. The acronym for the lateral surface area is LSA.

The calculation of the total area of all surfaces is called the Cumulative Surface Region in a closed shape. For example, we get its Total Surface Area in a cuboid by adding the area of all six surfaces. The acronym for the total surface area is TSA.

One square unit is simply the one-unit square area. When we quantify some surface area, we relate to the sides of one block square in order to know how many these units will fit in the figure given.

One cubic unit is the one-unit volume filled by a side cube. When we calculate the volume of any number, we actually refer to this cube of side one unit and how many these component cubes will fit in the defined closed form.

As our introduction to mensuration and the relevant words are over, let’s switch for the equations for mensuration, as, this is a discussion focused on an equation. The 2D figure has a list of formulas of measurement that define a relationship between the various parameters. Let’s look into detail about the estimation equations of some kinds.

Area (A) = (side)2 sq. units.

Perimeter (P) = (4 × sides) units.

Diagonal, d = \[\sqrt{2Xside}\] units.

Area = (length × breadth) sq. units.

Perimeter = 2(length + breadth) units.

Diagonal, d = \[\sqrt{length^{2}+breadth^{2}}\] units.

Area, A = \[\frac{heightXbase}{2}\]sq. units

Perimeter = (side a + side b + side c) units.

Area = \[\frac{\sqrt{3}}{4}\] x \[side^{2}\] sq. units.

Perimeter = (3 × side) units.

Area = \[\frac{heightXbase}{2}\] sq. units.

Perimeter = (2×side + base) units.

Area = \[\frac{legaXlegb}{2}\] sq. units.

Perimeter = lega + legb + \[\sqrt{(lega)^{2}+(legb)^{2}}\] units.

Hypotenuse = \[\sqrt{(lega)^{2}+(legb)^{2}}\] units.

Area = π x radius² sq. units.

Circumference = 2π x radius units.

Diameter, D = 2 x radius units.

The 3D figure has a list of formulas for measurement that define a relationship between the various parameters. Let’s look into the details about the estimation equations of some kinds.

Volume = cubic units.

Lateral Surface Area = 4×side2 sq. units.

Total Surface Area = 6× side2 sq. units.

Diagonal length d = \[\sqrt{(length)^{2}+(width)^{2}+(height)^{2}}\] units.

Volume = (length+width+height) cubic units.

Lateral Surface Area = 2×height (length + width) sq. units.

Total Surface Area = 2(length × width + length × height + height × width) sq. units.

Diagonal length = length2 + breadth2 + height2 units.

Volume = \[\frac{4}{3}\]𝜋 x radius³ cubic units.

Surface Area = 4𝜋 x radius² sq. units.

Volume = \[\frac{2}{3}\]𝜋 x radius³ cubic units.

Total Surface Area = 3𝜋 x radius² sq. units.

Volume = (𝜋 x radius² x height) cubic units.

Curved Surface Area (excluding the areas of the top and bottom circular regions) = (2𝜋Rh) sq. units.

Where, R = radius

Total Surface Area = (2𝜋Rh + 2𝜋R²) sq. units

Volume = \[\frac{1}{3}\]𝜋 x radius² x height cubic units.

Curved Surface Area = 𝜋 x radius x height sq. units.

Total Surface Area = 𝜋 x radius(length + height) sq. units

Slant Height of Cone \[\sqrt{height^{2}+(base radius)^{2}}\]sq. units.

Using these above formulas for the mensuration, most of the mensuration problems can be solved.