9-4 Polygons in the Coordinate Plane
Learn to draw polygons in the
coordinate plane and find the lengths
of their sides.
9-4 Polygons in the Coordinate Plane
Helpful Hint
Remember that in a rectangle, opposite
sides have equal length.
9-4 Polygons in the Coordinate Plane
Additional Example 1: Drawing Polygons in the
Coordinate Plane
Graph the triangle with vertices F(2, 5), G(4, 1),
and H(0, 22).
Graph each point on the
coordinate plane.
Then connect the points
with straight lines to form
a polygon.
9-4 Polygons in the Coordinate Plane
Check It Out: Example 1
Graph the triangle with vertices A(1, 2), B(4, 2),
and C(3, 1).
Graph each point on the
coordinate plane.
Then connect the points
with straight lines to form a
polygon.
9-4 Polygons in the Coordinate Plane
Additional Example 2: Finding Distance in the
Coordinate Plane
Find the perimeter of the rectangle.
Step 1: Find the length and
width.
To find the length of the
rectangle, count from left to
right along the x-axis from –1
to 3. The length is 4 units
long. To find the width, count
up the y-axis from –2 to 4.
The width is 6 units long.
9-4 Polygons in the Coordinate Plane
Additional Example 2: Continued
Step 2: Find the perimeter. Use the formula for the
perimeter of a rectangle.
Length of the rectangle = l
Width of the rectangle = w
Perimeter = 2l + 2w
P = 2(4) + 2(6) = 20
The perimeter of the rectangle is 20 units.
9-4 Polygons in the Coordinate Plane
Check It Out: Example 2
Find the perimeter of the rectangle.
Step 1: Find the length and
width.
To find the length of the
rectangle, count from left to
right along the x-axis from 5
to 8. The length is 3 units
long. To find the width, count
up the y-axis from 0 to 10.
The width is 10 units long.
9-4 Polygons in the Coordinate Plane
Continued: Check It Out: Example 2
Step 2: Find the perimeter. Use the formula for
the perimeter of a rectangle.
Length of the rectangle = l
Width of the rectangle = w
Perimeter = 2l + 2w
P = 2(3) + 2(10) = 26
The perimeter of the rectangle is 26 units.
9-4 Polygons in the Coordinate Plane
Additional Example 3: Social Studies Application
Candice’s house is at the corner of 3rd Avenue
and 7th Street. She walks from her house
west to Minus 2nd Avenue, then south to 4th
Street, then east to 3rd Avenue, and then back
home. How far did she walk?
Step 1: Plot the points and draw the rectangle.
Step 2: Find the length and width of the rectangle.
Step 3: Find the perimeter.
Perimeter = 2l + 2w
P = 2(5) + 2(3) = 16
Candice walked 16 blocks.
9-4 Polygons in the Coordinate Plane
Check It Out: Example 3
A polygon has vertices at (2, 4), (3, 4), (3, 1),
and (2, 1). What type of polygon is this? What
is its perimeter?
The polygon is a rectangle. The perimeter is 8 units