Mensuration : Length, Area, and Volume : Perimeter: Square, Rectangle, Triangle, Polygons

maths > mensuration-basics

Perimeter: Square, Rectangle, Triangle, Polygons

what you'll learn...

Overview

Perimeter :
Perimeter of a figure is the length of the line or curve forming the boundary of the figure.

Perimeter of square $= 4 \times side$ $=4 xx text( side)$

Perimeter of rectangle $= 2 \times length + width$ $=2 xx text( length + width)$

Perimeter of triangle $= sum of three sides$ $=text( sum of three sides)$

Perimeter of polygon $= sum of sides$ $=text( sum of sides)$

perimeter

The measure of length is the "distance-span between two points".

Perimeter of a figure is the length of the line or curve forming the boundary of the figure.

The word "perimeter" means: measure around a shape.

Perimeter is from the Greek root words peri (around) and meter (measure).

The perimeter of a square of side $3$ $3$ cm is $3 + 3 + 3 + 3 = 4 \times 3 = 12$ $3+3+3+3 = 4xx3 = 12$ cm.

Perimeter of a square is $4$ $4$ times the length of the side.

The perimeter of a rectangle of length $6$ $6$ cm and width $4$ $4$ cm is $6 + 4 + 6 + 4 = 2 \times (6 + 4) = 20$ $6 + 4 + 6 + 4 = 2 xx (6 + 4) = 20$ cm.

Perimeter of a rectangle is twice the sum of length and width.

The perimeter of a triangle of sides $6$ $6$ cm, $5$ $5$ cm, and $4$ $4$ cm is $6 + 5 + 4 = 15$ $6 + 5+ 4 = 15$ cm.

The perimeter of a triangle is sum of the lengths of the three sides.

The perimeter of a polygon of sides, $6$ $6$ cm, $2$ $2$ cm, $5$ $5$ cm, $4$ $4$ cm, and $6$ $6$ cm is $6 + 2 + 5 + 4 + 6 = 23$ $6 + 2 + 5 + 4 + 6 = 23$ cm.

Perimeter of a polygon is the sum of the lengths of its sides.

examples

What is the perimeter of a equilateral triangle with sides, $1$ $1$ cm?
The answer is " $1 + 1 + 1 = 3$ $1+1+1 = 3$ centimeter".

What is the perimeter of a rectangle formed by joining $2$ $2$ squares of side $3$ $3$ cm?
The answer is " $18$ $18$ cm".

Two squares are joined and the rectangle has length $3 + 3 = 6$ $3+3=6$ cm and height $3$ $3$ cm.
So the perimeter is $2 (6 + 3) = 18$ $2(6+3) = 18$ cm.

What is the perimeter of regular pentagon of side $2$ $2$ cm?
The answer is " $10$ $10$ cm".

summary

Outline

The outline of material to learn "Mensuration basics : Length, Area, & Volume" is as follows.

Note: click here for detailed outline of Mensuration (Basics).

• Measuring Basics

→ Introduction to Standards

→ Measuring Length

→ Accurate & Approximate Meaures

→ Measuring Area

→ Measuring Volume

→ Conversion between Units of Measure

• 2D shapes

→ Perimeter of Polygons

→ Area of Square & rectangle

→ Area of Triangle

→ Area of Polygons

→ Perimeter and area of a Circle

→ Perimeter & Area of Quadrilaterals

• 3D shapes

→ Surface Area of Cube, Cuboid, Cylinder

→ Volume of Cube, Cuboid, Cylinder