Step by step
The question
Question: find the perimeter of the rectangle with corners (1, 1), (5, 1), (5, 4), (1, 4).
rectangle: (1, 1), (5, 1), (5, 4), (1, 4)
1 Plot the points
We put the corners on the grid.
Corner A is (1, 1).
And so on.
We join them in order.
2 Find the side lengths
A B: the same y, so it goes across.
Its length is the bigger x minus the smaller: 5 minus 1 is 4.
= AB: 5 − 1 = 4
B C: the same x, so it goes up and down.
Its length is the bigger y minus the smaller: 4 minus 1 is 3.
= BC: 4 − 1 = 3
3 Perimeter
The perimeter is the way round: all four sides.
= perimeter = all four sides
Careful!
Not just two sides.
The way round has four sides.
Careful: not 4 + 3 = 7 ✗
4 plus 3 plus 4 plus 3 is 14 units.
= perimeter = 4 + 3 + 4 + 3 = 14 units
4 Check
Let's check: opposite sides are the same.
So it is 2 times 4 plus 3: 2 times 7 is 14.
So the answer is right!
2 × (4 + 3) = 2 × 7 = 14
Let's look back.
First: plot the points.
Then: find the side lengths.
Then: perimeter.
Last: check.
Answer
= perimeter = 4 + 3 + 4 + 3 = 14 units