Perimeter is the distance around a 2-dimensional object. We use perimeter to measure the distance around the yard so we can order the correct amount of fencing. We can also use perimeter to measure the distance around a room to plan for installing base boards. For perimeter of a square, triangle or rectangle you simple add each side up or multiply the length by 2 and the width by 2
Example: Lisa and Mike would like to install a new fence around their property. They would like to put in a wood fence that is 6’ tall so their dogs can’t get out. The width of their yard is 50 feet and the length is 40 feet. They will also need to put in a post every six feet to secure the fencing. The posts cost $13.50 each. Fencing costs $8.50 per foot.
Problem
1: Calculate the perimeter of their yard.
Solution 1: P = 2W + 2L
P = 2 x 50 feet + 2 x 40 feet
P = 180 feet Problem
2: How many posts do they need?
Solution 2: 180 feet ÷ 6 feet = 30 posts
Problem
3: How much will it cost in materials for the fence?
Solution 3: Posts 30 posts x $ 13.50 = $405 Fencing 180 feet x $8.50 = $1530 Total $405 + $1530 = $1960
The total cost for the materials for the fence is $1960
Tim and Susie would like to put baseboard in each room. Answer the following questions using the diagram below.
1. Find the overall perimeter of the family room.
2. There are three doors in the family room – one going to the entrance, one going to the front porch and one going to the bedroom. The door going to the entrance is 3 feet wide, the door going to the front porch is 5 feet wide and the door going to the bedroom is 3 feet wide. Recalculate your perimeter.
3. The baseboard that they would like to install is $7.89 per foot. How much would it cost them in materials for baseboard for the family room?
4. Find the perimeter and cost for the baseboard for all the other rooms – all the doors in these rooms are 3 feet wide.
a. Bedroom
b. Laundry room
c. Entrance
5. How much will it cost altogether for the base board?
1) P= (2 x 18 + (2 x 8) = 52 feet
2) 52 - (3 + 5+ 3) = 41 feet
3) 41 x $7.89 = $323.49
4a) (2x9) + (2x8)-3 =37 feet, 37x $7.89 = $291.93
4b) (2x9)+ (2x5)-3 = 31 feet, 31 x $7.89 = $244.59
4c) (2x6) + (2x6)-3 -3 = 18 feet, 18 x $7.89 = $142.02
5) $1002.03