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Study Guides > Prealgebra

Using Linear, Square, and Cubic Measure Appropriately

Learning Outcomes

  • Given an item to measure determine whether you would use linear, square, or cubic units
  • Calculate perimeter and area of a rectangle
 

When you measure your height or the length of a garden hose, you use a ruler or tape measure (see below). A tape measure might remind you of a line—you use it for linear measure, which measures length. Inch, foot, yard, mile, centimeter and meter are units of linear measure.

This tape measure measures inches along the top and centimeters along the bottom. A picture of a portion of a tape measure is shown. The top shows the numbers 1 through 5. The portion from the beginning to the 1 has a red circle and an arrow to a picture from 0 to 1 inch, with 1 sixteenth, 1 eighth, 3 eighths, 1 half, and 3 fourths labeled. Above this, it is labeled When you want to know how much tile is needed to cover a floor, or the size of a wall to be painted, you need to know the area, a measure of the region needed to cover a surface. Area is measured is square units. We often use square inches, square feet, square centimeters, or square miles to measure area. A square centimeter is a square that is one centimeter (cm) on each side. A square inch is a square that is one inch on each side (see below). Square measures have sides that are each 11 unit in length. Two squares are shown. The smaller one has sides labeled 1 cm and is 1 square centimeter. The larger one has sides labeled 1 inch and is 1 square inch. The next image shows a rectangular rug that is 22 feet long by 33 feet wide. Each square is 11 foot wide by 11 foot long, or 11 square foot. The rug is made of 66 squares. The area of the rug is 66 square feet. The rug contains six squares of 11 square foot each, so the total area of the rug is 66 square feet. A rectangle is shown. It has 3 squares across and 2 squares down, a total of 6 squares. When you measure how much it takes to fill a container, such as the amount of gasoline that can fit in a tank, or the amount of medicine in a syringe, you are measuring volume. Volume is measured in cubic units such as cubic inches or cubic centimeters. When measuring the volume of a rectangular solid, you measure how many cubes fill the container. We often use cubic centimeters, cubic inches, and cubic feet. A cubic centimeter is a cube that measures one centimeter on each side, while a cubic inch is a cube that measures one inch on each side (see below). Cubic measures have sides that are 11 unit in length. Two cubes are shown. The smaller one has sides labeled 1 cm and is labeled as 1 cubic centimeter. The larger one has sides labeled 1 inch and is labeled as 1 cubic inch. Suppose the cube in the image below measures 33 inches on each side and is cut on the lines shown. How many little cubes does it contain? If we were to take the big cube apart, we would find 2727 little cubes, with each one measuring one inch on all sides. So each little cube has a volume of 11 cubic inch, and the volume of the big cube is 2727 cubic inches. A cube that measures 33 inches on each side is made up of 2727 one-inch cubes, or 2727 cubic inches. A cube is shown, comprised of smaller cubes. Each side of the cube has 3 smaller cubes across, for a total of 27 smaller cubes. Doing the Manipulative Mathematics activity Visualizing Area and Perimeter will help you develop a better understanding of the difference between the area of a figure and its perimeter.

example

For each item, state whether you would use linear, square, or cubic measure: 1. amount of carpeting needed in a room 2. extension cord length 3. amount of sand in a sandbox 4. length of a curtain rod 5. amount of flour in a canister 6. size of the roof of a doghouse. Solution
1. You are measuring how much surface the carpet covers, which is the area. square measure
2. You are measuring how long the extension cord is, which is the length. linear measure
3. You are measuring the volume of the sand. cubic measure
4. You are measuring the length of the curtain rod. linear measure
5. You are measuring the volume of the flour. cubic measure
6. You are measuring the area of the roof. square measure
 

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[ohm_question]146501[/ohm_question]
  Many geometry applications will involve finding the perimeter or the area of a figure. There are also many applications of perimeter and area in everyday life, so it is important to make sure you understand what they each mean. Picture a room that needs new floor tiles. The tiles come in squares that are a foot on each side—one square foot. How many of those squares are needed to cover the floor? This is the area of the floor. Next, think about putting new baseboard around the room, once the tiles have been laid. To figure out how many strips are needed, you must know the distance around the room. You would use a tape measure to measure the number of feet around the room. This distance is the perimeter.

Perimeter and Area

The perimeter is a measure of the distance around a figure. The area is a measure of the surface covered by a figure.
  The image below shows a square tile that is 11 inch on each side. If an ant walked around the edge of the tile, it would walk 44 inches. This distance is the perimeter of the tile. Since the tile is a square that is 11 inch on each side, its area is one square inch. The area of a shape is measured by determining how many square units cover the shape. Perimeter=4inchesArea=1square inch\begin{array}{c}\text{Perimeter}=4\text{inches}\\ \text{Area}=1\text{square inch}\end{array} When the ant walks completely around the tile on its edge, it is tracing the perimeter of the tile. The area of the tile is 11 square inch. A 5 square by 5 square checkerboard is shown with each side labeled 1 inch. An image of an ant is shown on the top left square. Doing the Manipulative Mathematics activity Measuring Area and Perimeter will help you develop a better understanding of how to measure the area and perimeter of a figure.

example

Each of two square tiles is 11 square inch. Two tiles are shown together. 1. What is the perimeter of the figure? 2. What is the area? A checkerboard is shown. It has 10 squares across the top and 5 down the side.

Answer: Solution 1. The perimeter is the distance around the figure. The perimeter is 66 inches. 2. The area is the surface covered by the figure. There are 22 square inch tiles so the area is 22 square inches. A checkerboard is shown. It has 10 squares across the top and 5 down the side. The top and bottom each have two adjacent 1 inch labels across, the sides have 1 inch labels.

 

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[ohm_question]146926[/ohm_question]  
   

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