Step by step
The question
Question: find the perimeter of the rectangle with corners (−5, −2), (−1, −2), (−1, 4), (−5, 4).
rectangle: (−5, −2), (−1, −2), (−1, 4), (−5, 4)
1 Plot the points
We put the corners on the grid.
Corner A is (−5, −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 −5 is 4.
= AB: −1 − (−5) = 4
B C: the same x, so it goes up and down.
Its length is the bigger y minus the smaller: 4 minus −2 is 6.
= BC: 4 − (−2) = 6
Careful!
−2 is on the other side of 0.
Minus a negative is plus: 4 plus 2.
Careful: not 4 − 2 = 2 ✗
3 Perimeter
The perimeter is the way round: all four sides.
= perimeter = all four sides
4 plus 6 plus 4 plus 6 is 20 units.
= perimeter = 4 + 6 + 4 + 6 = 20 units
4 Check
Let's check: opposite sides are the same.
So it is 2 times 4 plus 6: 2 times 10 is 20.
So the answer is right!
2 × (4 + 6) = 2 × 10 = 20
Let's look back.
First: plot the points.
Then: find the side lengths.
Then: perimeter.
Last: check.
Answer
= perimeter = 4 + 6 + 4 + 6 = 20 units