ISEE Lower Level Math : How to find the area of a rectangle
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Example Questions
Example Question #21 : How To Find The Area Of A Rectangle
If a rectangle has a perimeter of 40, a width of 4, and a length of 4x, what is the value of x?
The perimeter of a rectangle is equal to 
Thus, 
Add like terms:
Subtract 8 from both sides:
Divide both sides by 8:
Example Question #22 : How To Find The Area Of A Rectangle
A rectangle has a perimeter of 30. One of its sides has a length of 6. What is its area?
If the rectangle has one side that is 
If the perimeter is 30, you know that the following equation holds:
This means that the other two sides can be found by solving for 
The area of a rectangle is equal to its base times its height:
Example Question #22 : How To Find The Area Of A Rectangle
A rectangle has two sides that are each 
If one side is 
The area of a rectangle is equal to its base times its height:
Example Question #22 : How To Find The Area Of A Rectangle
What is the area of the following rectangle?
The area of a rectangle is defined as the base multiplied by its height. Therefore, for this rectangle:
Example Question #25 : How To Find The Area Of A Rectangle
One side of a rectangle has a length of 10. What is the area of this rectangle if it has a perimeter of 120?
Based on what we were told, our rectangle looks like this:
We know, therefore, that there is 
The area of a rectangle is its base times its height. Therefore, the area is:
Example Question #26 : How To Find The Area Of A Rectangle
A rectangle has a width of 
To find the area of a rectangle apply the formula:
This problem provides the measurements for both the width and length of the rectangle.
Thus, the solution is:
Example Question #24 : How To Find The Area Of A Rectangle
A rectangle has a width of 
Not enough information is provided.
In this problem you are given the width and perimeter of the rectangle. However, to solve for the area of the rectangle you must first find the length of the rectangle. To do so, work backwards using the formula:
Now that you know the width and length of the rectangle, apply the area formula: 
Example Question #53 : Geometry
Find the area of the rectangle shown above.
To find the area of a rectangle apply the formula:
The image provides the measurements for both the width and length of the rectangle.
Thus, the solution is:
Tip for mental math: Since you are multiplying 
Example Question #61 : Geometry
A rectangle has a length of 
To solve this problem, first note that the width of the rectangle must equal:
Now that you know the width and length of the rectangle, apply the area formula: 
Example Question #41 : Quadrilaterals
A rectangle has a width of 
To find the area of a rectangle apply the formula:
This problem provides the measurements for both the width and length of the rectangle.
Thus, the solution is: 
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