Perimeter

Perimeter

Real-world Examples

How is perimeter used in everyday life?

Fences

We would need to know how much fence to put around a garden.

Swimming Pool

We need to know how much concrete to put around the pool.

Christmas lights

We often find the perimeter when putting up Christmas lights around the house.

Border

We find the perimeter of a room to figure out how much wallpaper border to put up.

Track and Field

Athletes use the perimeter of the track to run relays.

We can calculate the perimeter of this square by adding 5+5+5+5 or 5x4 ...

which equals 20.

STAAR Reference Chart

You can use the reference chart to use the formulas to find the perimeter of a square and rectangle.

Square Formula

Square P= 4s mean Perimeter = 4 X sides (There are 4 sides in a square and all sides are equal.)

Rectangle Formula

P = l + w + L + w means

Perimeter = length + width + length + width

-or-

P = 2l + 2w means

Perimeter = 2 times length + 2 times width

Let's answer some questions.

Ready?

Find the perimeter for this square and mark your answer on the next slide.

You can use the easy formula P = 4s

(P = 4 X ___ to get your answer.)

Multiple Choice

What is the perimeter of this square?

• 3 units

• 6 units

• 9 units

• 12 units

What is the perimeter of this triangle?

Be ready to answer on the next slide.

Multiple Choice

What's the perimeter of this triangle?

• 10 cm

• 11 cm

• 12 cm

• 13 cm

What's the perimeter of this triangle?

Be ready to answer on the next slide.

Multiple Choice

What's the perimeter of this triangle?

• 18 inches

• 18 feet

• 18 cm

What's the perimeter of this pentagon?

Be ready to choose your answer on the next slide.

Multiple Choice

What is the perimeter of this pentagon?

• 15 units

• 12 units

• 9 units

• 6 units

Let's challenge ourselves a little bit!

• Not all of the sides are labeled.

• You can still figure out the lengths of the unlabeled sides by looking at the sides on the opposite side.

• Remember the formula to find the perimeter of a rectangle?

• Hint: L = 7 in and w = 2 in

• P= l + w + l + w

Multiple Choice

What is the perimeter of this shape?

• 11 inches

• 22inches

What's the perimeter of this rectangle?

Multiple Choice

What's the perimeter of this rectangle?

• 26 cm

• 27 cm

• 28 cm

Multiple Choice

What is the perimeter of this rectangle?

• 16 ft

• 8 ft

• 32 ft

LAST QUESTION!

Multiple Choice

• 28 in

• 7 in

• 14 in