The lines that make up this rectangle
ARE the perimeter.
The space inside is the AREA
We have 2 pieces of information
The LENGTH
and the WIDTH
And that's ALL we need
These 2 sides are equal
And these 2 sides are equal
Adding up all 4 sides is...
Let's keep going,
and take a look
at Strategy Number 2
2 LENGTHS the same...
And 2 WIDTHS the same.
So we can use DOUBLING as a strategy
The length is 7cm
The width is 3cm
Next: add up these doubled values
to get the perimeter
The formula for this strategy is...
We make sense out of it
by re-writing the formula
using the measurements from the diagram
And these parts are in brackets
because of course, we do those FIRST
and THEN we do the adding at the end.
2x4=8
plus...
2x11=22
Then just add those figures together!
This formula CLEARLY tells us what to do.
You can DO this!
Now let's take a look at...
Strategy Number 3!
You can think of a rectangle
as being made up of...
These are called 'Adjacent Sides'
These sides are 'next to' each other
They JOIN at a corner!
In Strategy #3...
So we multiply by 2
And there's a formula for this too!
The brackets are telling us:
'Add the length and width first'
The the 2 outside the brackets
tells us to multiply by 2
And there's the perimeter!
Don't forget: unit of measurement at the end!
This strategy ONLY has
2 calculations!
That makes THIS...
...to find the perimeter of a rectangle!
And that's why...
You have 3 strategies
so you get used to using it
You are going to ROCK
the perimeter of a rectangle!