Step by step
The question
Question: find the perimeter of the rectangle with corners (−4, 2), (1, 2), (1, 6), (−4, 6).
rectangle: (−4, 2), (1, 2), (1, 6), (−4, 6)
1 Plot the points
We put the corners on the grid.
Corner A is (−4, 2).
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: 1 minus −4 is 5.
= AB: 1 − (−4) = 5
Careful!
−4 is on the other side of 0.
Minus a negative is plus: 1 plus 4.
Careful: not 1 − 4 = -3 ✗
B C: the same x, so it goes up and down.
Its length is the bigger y minus the smaller: 6 minus 2 is 4.
= BC: 6 − 2 = 4
3 Perimeter
The perimeter is the way round: all four sides.
= perimeter = all four sides
5 plus 4 plus 5 plus 4 is 18 units.
= perimeter = 5 + 4 + 5 + 4 = 18 units
4 Check
Let's check: opposite sides are the same.
So it is 2 times 5 plus 4: 2 times 9 is 18.
So the answer is right!
2 × (5 + 4) = 2 × 9 = 18
Let's look back.
First: plot the points.
Then: find the side lengths.
Then: perimeter.
Last: check.
Answer
= perimeter = 5 + 4 + 5 + 4 = 18 units