__maths__>__Mensuration : Length, Area, and Volume__>__Mensuration: 2D Shapes__### Perimeter: Square, Rectangle, Triangle, Polygons

*In the topic "mensuration", the foundation focuses on learning • what is measurement standard? • Absolute and Derived Standards • Measurement by superimposition • Measurement by calculation • Measurement by equivalence (infinitesimal and Cavalieri's principle in 2D and 3D. )*

Finding perimeter of simple figures (squares, rectangle, triangle, polygon) are revised without much discussion.

*click on the content to continue..*

Which of the following is a meaning for the word "perimeter"?

- measure around a shape
- measure around a shape
- half of a kind of hot sauce

The answer is "measure around a shape". Perimeter is from the Greek root words peri (around) and meter (measure).

What is the term used to refer "measure around a shape"?

- Pronunciation : Say the answer once

Spelling: Write the answer once

The answer is "perimeter".

Which of the following is the measure of length?

- distance-span between two points
- distance-span between two points
- surface-span within a closed shape
- space-span within a closed solid

The answer is "distance-span between two points"

What is the perimeter of a square of side `4cm`?

- `4cm`
- `16cm`
- `16cm`

The answer is "`16cm`". *Perimeter of a square is `4` times the length of the side.*

What is the perimeter of a rectangle of length `6cm` and width `4cm`?

- `20cm`
- `20cm`
- `10cm`

The answer is "`20cm`". *Perimeter of a rectangle is twice the sum of length and width.*

What is the perimeter of a triangle of sides `6cm`, `5cm`, and `4cm`?

- `15cm`
- `15cm`
- `30cm`

The answer is "`15cm`". *The perimeter of a triangle is sum of the lengths of the three sides.*

What is the perimeter of a polygon of sides, `6cm`, `2cm`, `5cm`, `4cm`, and `6cm` ?

- `23cm`
- `23cm`
- `19cm`

The answer is "`23cm`". *Perimeter of a polygon is the sum of the lengths of its sides.*

**Perimeter ** :

Perimeter of square `=4 xx text( side)`

Perimeter of rectangle `=2 xx text( length + width)`

Perimeter of triangle `=text(sum of sides)`

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

*Solved Exercise Problem: *

What is the perimeter of a equilateral triangle with sides, `1`cm?

- `1`cm
- `3` centimeter
- `3` centimeter

The answer is "`3` centimeter"

*Solved Exercise Problem: *

What is the perimeter of a rectangle formed by joining `2` squares of side `3` cm?

- `12`cm
- `24`cm
- `18`cm
- `18`cm

The answer is "`18`cm".

Two squares are joined and the rectangle has length `3+3=6`cm and height `3`cm.

So the perimeter is `2(6+3) = 18cm`.

*Solved Exercise Problem: *

What is the perimeter of regular pentagon of side `2`cm?

- `10`cm
- `10`cm
- `5`cm

The answer is "`10`cm".

*slide-show version coming soon*