Transcript Irregular shapes - Rutherford County Schools

Irregular shapes
perimeter
Objective

0506.4.2 Decompose irregular shapes to
find perimeter and area.
Remember!!!
Perimeter
 all sides added together

Review of perimeter

http://www.jogtheweb.com/run/deYhoh
v5NJMJ/Area-and-Perimeter#1
Find the perimeter
12 cm
P = 64 cm
20 cm
Find the perimeter
P = 47 in
15 in
15 in
17 in
What is an irregular shape?
Try to make an irregular shape
using the shapes you have…
How
do you think you find the
perimeter of your shape? Write down
your answer.
Perimeter of irregular shapes
You still add all the sides together to find
the perimeter.
 Try this one.

Find the perimeter
6 cm
1 cm
1 cm
2 cm
4 cm
4 cm
2 cm
P = 32 cm
2 cm
2 cm
1 cm
1 cm
6 cm
2 cm
Can you find the perimeter even
when they don’t give you all the
sides?
7 cm
2 cm
P = 44 cm
7 cm
Using your shapes and a piece of
paper:
Make 2 dimensional irregular shapes
using the pieces you have in front of you.
 Make at least 5 shapes.
 Then using your ruler, find the perimeter
using centimeters.

Make one and trade
You are going to make one on a blank
sheet of paper.
 First, measure it so you know the
perimeter.
 Next, put the answer on the back, very
small and light.
 Then, we are going to walk around the
room and work each others problems.
 Finally, we will check answers.
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Homework
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Worksheet irregular perimeter