Grade 4 - Progress in Mathematics

Update your skills. See page 20.

Use Perimeter Formulas

11-1

formula for perimeter

of a rectangle

formula for

perimeter of

a square

formula for

perimeter of

an equilateral

triangle

3 ft side 6 cm side

Perimeter is the distance around a figure.

Yo u can use a formula to find

the perimeter of a rectangle.

What is the perimeter of this

rectangle?

perimeter 
length width length width

P 
 
  w  
  w

P 
 ( 2  ( 2 w

P 
 (2  10 ) (2  4 )

P 
 20  8

P 
 28 m

The perimeter of the rectangle is 28 m.

Yo u can also use formulas to find the perimeter

of a square and of an equilateral triangle.

P
side side side side P
side side side

P
ssss P
sss

P
 4 s P
 3 s

P
 4  3 P
 3  6

P
12 ft P
18 cm

10 m

4 m

length

width

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