Math › How to find the area of a square
How much more area does a square with a side of 2r have than a circle with a radius r? Approximate π by using 22/7.
12/14 square units
1/7 square units
4/7 square units
6/7 square units
The area of a circle is given by A = πr2 or 22/7r2
The area of a square is given by A = s2 or (2r)2 = 4r2
Then subtract the area of the circle from the area of the square and get 6/7 square units.
If a completely fenced-in square-shaped yard requires 140 feet of fence, what is the area, in square feet, of the lot?
35
70
140
1225
4900
Since the yard is square in shape, we can divide the perimeter(140ft) by 4, giving us 35ft for each side. We then square 35 to give us the area, 1225 feet.
Find the area of a square with a diagonal of .
Not enough information to solve
A few facts need to be known to solve this problem. Observe that the diagonal of the square cuts it into two right isosceles triangles; therefore, the length of a side of the square to its diagonal is the same as an isosceles right triangle's leg to its hypotenuse: .
Rearrange an solve for .
Now, solve for the area using the formula .
ABCD and EFGH are squares such that the perimeter of ABCD is 3 times that of EFGH. If the area of EFGH is 25, what is the area of ABCD?
5
15
25
75
225
Assign variables such that
One side of ABCD = a
and One side of EFGH = e
Note that all sides are the same in a square. Since the perimeter is the sum of all sides, according to the question:
4a = 3 x 4e = 12e or a = 3e
From that area of EFGH is 25,
e x e = 25 so e = 5
Substitute a = 3e so a = 15
We aren’t done. Since we were asked for the area of ABCD, this is a x a = 225.
If the perimeter of a square is equal to twice its area, what is the length of one of its sides?
Area of a square in terms of each of its sides:
Area = S x S
Perimeter of a square:
Perimeter = 4S
So if 'the perimeter of a square is equal to twice its area':
2 x Area = Perimeter
2 x \[S x S\] = \[4S\]; divide by 2:
S x S = 2S; divide by S:
S = 2
What is the area of a square with a diagonal of ?
The formula for the area of a square is . However, the problem gives us a diagonal and not a side.
Remember that all sides of a square are equal, so the diagonal cuts the square into two equal triangles, each a right triangle.
If we use the Pythagorean Theorem, we see:
Plug in our given diagonal to solve.
From here we can plug our answer back into our original equation:
If the diagonal of a square measures , what is the area of the square?
This is an isosceles right triangle, so the diagonal must equal times the length of a side. Thus, one side of the square measures
, and the area is equal to
A half circle has an area of . What is the area of a square with sides that measure the same length as the diameter of the half circle?
72
36
144
81
108
If the area of the half circle is , then the area of a full circle is twice that, or
.
Use the formula for the area of a circle to solve for the radius:
36π = πr2
r = 6
If the radius is 6, then the diameter is 12. We know that the sides of the square are the same length as the diameter, so each side has length 12.
Therefore the area of the square is 12 x 12 = 144.
If the ratio of the sides of two squares is , what is the ratio of the areas of those two squares?
Express the ratio of the two sides of the squares as . The area of each square is one side multiplied by itself, so the ratios of the areas would be
. The right side of this equation simplifies to a ratio of
.
Eric has 160 feet of fence for a parking lot he manages. If he is using all of the fencing, what is the area of the lot assuming it is square?
The area of a square is equal to its length times its width, so we need to figure out how long each side of the parking lot is. Since a square has four sides we calculate each side by dividing its perimeter by four.
Each side of the square lot will use 40 feet of fence.
.