Student Help Card

Lesson 7: Represent Polygons on the Coordinate Plane6.GR.3

Stuck? Start here. Read the steps, try the problem, then check your answer.

I can…

I can draw polygons from their vertex coordinates on the coordinate plane, and use coordinates to find side lengths and solve perimeter and area problems.

Key words

  • vertex — A corner where edges or sides meet.
  • polygon — A closed shape with straight sides.
  • perimeter — The distance around a shape.
  • distance between vertices — How far apart two corners are.
  • scale — What one grid unit stands for.
  • Side length — How long one side is.

Steps

  1. (-4.5, 3) and (5, 3) share y = 3, so the side between them is horizontal.
  2. Its length is the distance between the x-coordinates: |5 − (−4.5)| = 9.5 units.
  3. (5, 3) and (5, -3.75) share x = 5, so that side is vertical: |3 − (−3.75)| = 6.75 units.

Try it

A rectangle has vertices (-3, 2), (4, 2), (4, -3), (-3, -3). What is its perimeter?

Check your answer

24 units

Width |4 − (−3)| = 7, height |2 − (−3)| = 5. Perimeter = 2(7) + 2(5) = 24 units.

Sentence starter

I know ___ because ___.

Goal: I can explain how I found a distance using the words vertices, coordinates, and absolute value.