How to find circumference - Basic Geometry
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A circle with an area of 13_π_ in2 is centered at point C. What is the circumference of this circle?
A circle with an area of 13_π_ in2 is centered at point C. What is the circumference of this circle?
The formula for the area of a circle is A = _πr_2.
We are given the area, and by substitution we know that 13_π_ = _πr_2.
We divide out the π and are left with 13 = _r_2.
We take the square root of r to find that r = √13.
We find the circumference of the circle with the formula C = 2_πr_.
We then plug in our values to find C = 2√13_π_.
The formula for the area of a circle is A = _πr_2.
We are given the area, and by substitution we know that 13_π_ = _πr_2.
We divide out the π and are left with 13 = _r_2.
We take the square root of r to find that r = √13.
We find the circumference of the circle with the formula C = 2_πr_.
We then plug in our values to find C = 2√13_π_.
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A 6 by 8 rectangle is inscribed in a circle. What is the circumference of the circle?
A 6 by 8 rectangle is inscribed in a circle. What is the circumference of the circle?
First you must draw the diagram. The diagonal of the rectangle is also the diameter of the circle. The diagonal is the hypotenuse of a multiple of 2 of a 3,4,5 triangle, and therefore is 10.
Circumference = π * diameter = 10_π_.
First you must draw the diagram. The diagonal of the rectangle is also the diameter of the circle. The diagonal is the hypotenuse of a multiple of 2 of a 3,4,5 triangle, and therefore is 10.
Circumference = π * diameter = 10_π_.
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Ashley has a square room in her apartment that measures 81 square feet. What is the circumference of the largest circular area rug that she can fit in the space?
Ashley has a square room in her apartment that measures 81 square feet. What is the circumference of the largest circular area rug that she can fit in the space?
In order to solve this question, first calculate the length of each side of the room.
The length of each side of the room is also equal to the length of the diameter of the largest circular rug that can fit in the room. Since 
, the circumference is simply
In order to solve this question, first calculate the length of each side of the room.
The length of each side of the room is also equal to the length of the diameter of the largest circular rug that can fit in the room. Since 
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A gardener wants to build a fence around their garden shown below. How many feet of fencing will they need, if the length of the rectangular side is 12 and the width is 8?
A gardener wants to build a fence around their garden shown below. How many feet of fencing will they need, if the length of the rectangular side is 12 and the width is 8?
The shape of the garden consists of a rectangle and two semi-circles. Since they are building a fence we need to find the perimeter. The perimeter of the length of the rectangle is 24. The perimeter or circumference of the circle can be found using the equation C=2π(r), where r= the radius of the circle. Since we have two semi-circles we can find the circumference of one whole circle with a radius of 4, which would be 8π.
The shape of the garden consists of a rectangle and two semi-circles. Since they are building a fence we need to find the perimeter. The perimeter of the length of the rectangle is 24. The perimeter or circumference of the circle can be found using the equation C=2π(r), where r= the radius of the circle. Since we have two semi-circles we can find the circumference of one whole circle with a radius of 4, which would be 8π.
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If a circle has an area of 
, what is the circumference of the circle?
If a circle has an area of
The formula for the area of a circle is πr2. For this particular circle, the area is 81π, so 81π = πr2. Divide both sides by π and we are left with r2=81. Take the square root of both sides to find r=9. The formula for the circumference of the circle is 2πr = 2π(9) = 18π. The correct answer is 18π.
The formula for the area of a circle is πr2. For this particular circle, the area is 81π, so 81π = πr2. Divide both sides by π and we are left with r2=81. Take the square root of both sides to find r=9. The formula for the circumference of the circle is 2πr = 2π(9) = 18π. The correct answer is 18π.
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A car tire has a radius of 18 inches. When the tire has made 200 revolutions, how far has the car gone in feet?
A car tire has a radius of 18 inches. When the tire has made 200 revolutions, how far has the car gone in feet?
If the radius is 18 inches, the diameter is 3 feet. The circumference of the tire is therefore 3π by C=d(π). After 200 revolutions, the tire and car have gone 3π x 200 = 600π feet.
If the radius is 18 inches, the diameter is 3 feet. The circumference of the tire is therefore 3π by C=d(π). After 200 revolutions, the tire and car have gone 3π x 200 = 600π feet.
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A circle has the equation below. What is the circumference of the circle?
(x – 2)2 + (y + 3)2 = 9
A circle has the equation below. What is the circumference of the circle?
(x – 2)2 + (y + 3)2 = 9
The radius is 3. Yielding a circumference of 
.
The radius is 3. Yielding a circumference of
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The diameter of a circle is defined by the two points (2,5) and (4,6). What is the circumference of this circle?
The diameter of a circle is defined by the two points (2,5) and (4,6). What is the circumference of this circle?
We first must calculate the distance between these two points. Recall that the distance formula is:√((x2 - x1)2 + (y2 - y1)2)
For us, it is therefore: √((4 - 2)2 + (6 - 5)2) = √((2)2 + (1)2) = √(4 + 1) = √5
If d = √5, the circumference of our circle is πd, or π√5.
We first must calculate the distance between these two points. Recall that the distance formula is:√((x2 - x1)2 + (y2 - y1)2)
For us, it is therefore: √((4 - 2)2 + (6 - 5)2) = √((2)2 + (1)2) = √(4 + 1) = √5
If d = √5, the circumference of our circle is πd, or π√5.
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What is the circumference of a circle with a radius of 
?
(Round your answer to the nearest tenth.)
What is the circumference of a circle with a radius of
(Round your answer to the nearest tenth.)
The circumference is given by the formula:
where 
is the radius.
The circumference is given by the formula:
where
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If this circle has a diameter of 12 inches, what is its circumference?
If this circle has a diameter of 12 inches, what is its circumference?
Know that the formula for circumference is 
, where C is the circumference and D is the diameter. It is given that the diameter is 12 inches. Therefore, the circumference is 
Know that the formula for circumference is
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If a circle has an area of 
, what is the circumference?
If a circle has an area of
For a circle, the formula for area is 
and the formula for circumference is 
, where 
is the radius and 
is the diameter.
Plug the known quantities into the area formula and solve for the radius:
Now plug this value into the circumference formula to solve:
For a circle, the formula for area is
Plug the known quantities into the area formula and solve for the radius:
Now plug this value into the circumference formula to solve:
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A circle is circumscribed around a square that has sides of 5cm. What is the perimeter of the circle?
A circle is circumscribed around a square that has sides of 5cm. What is the perimeter of the circle?
Because the circle is circumscribed around the square, the diagonal of the square is the same as the diameter of the circle. So to find the diagonal we use the Pythagorean Theorem:
So the equation to solve becomes 
or 
The perimeter, or circumference, of the circle is given by 
or 
Because the circle is circumscribed around the square, the diagonal of the square is the same as the diameter of the circle. So to find the diagonal we use the Pythagorean Theorem:
So the equation to solve becomes
The perimeter, or circumference, of the circle is given by
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Line 
is the radius of the circle shown and has a length of 7.5. What is the circumference of the circle?
Line
Plug in the given value for the radius to find the circumference:
Plug in the given value for the radius to find the circumference:
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Find the perimeter of the ice rink formed by the rectangle and semi-circles with the dimensions shown.
Find the perimeter of the ice rink formed by the rectangle and semi-circles with the dimensions shown.
The perimeter of the rink runs along the outside of the combined shapes. The two outer edges of the rectangle are 
each, so 
of the perimeter consists of those two sides.
The two semi-circles that form the remainder of the perimeter, and can be considered two halves of one circle. The diameter of the circle would be 
. The circumference of the circle would account for the outer edges of the two semi-circles in the ice rink. Find the circumference of the circle with the formula 
as follows.
Finally, add this circumference that accounts for the semi-circles to the length of the two sides formed by the rectangle to find the total perimeter of the rink.
The perimeter of the rink runs along the outside of the combined shapes. The two outer edges of the rectangle are
The two semi-circles that form the remainder of the perimeter, and can be considered two halves of one circle. The diameter of the circle would be
Finally, add this circumference that accounts for the semi-circles to the length of the two sides formed by the rectangle to find the total perimeter of the rink.
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The diameter of a circle is 16 centimeters. What is the circumference of the circle?
The diameter of a circle is 16 centimeters. What is the circumference of the circle?
To find the circumference of a circle, multiply the circle's diameter by pi (3.14).
To find the circumference of a circle, multiply the circle's diameter by pi (3.14).
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Find the circumference of a circle that has a radius of 
.
Find the circumference of a circle that has a radius of
Recall the formula for finding the circumference of a circle:
We can substitute in the value for the radius in order to find the circumference of the circle in question.
Solve.
Simplify.
Recall the formula for finding the circumference of a circle:
We can substitute in the value for the radius in order to find the circumference of the circle in question.
Solve.
Simplify.
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Find the circumference of a circle with a radius of 
.
Find the circumference of a circle with a radius of
Recall the formula for finding the circumference of a circle:
We can substitute in the value for the radius in order to find the circumference of the circle in question.
Solve.
Simplify.
Recall the formula for finding the circumference of a circle:
We can substitute in the value for the radius in order to find the circumference of the circle in question.
Solve.
Simplify.
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Find the circumference of the circle with a radius of 
.
Find the circumference of the circle with a radius of
Recall the formula for finding the circumference of a circle:
We can substitute in the value for the radius in order to find the circumference of the circle in question.
Solve.
Simplify.
Recall the formula for finding the circumference of a circle:
We can substitute in the value for the radius in order to find the circumference of the circle in question.
Solve.
Simplify.
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Find the circumference of a circle with a radius of 
.
Find the circumference of a circle with a radius of
Recall the formula for finding the circumference of a circle:
We can substitute in the value for the radius in order to find the circumference of the circle in question.
Solve.
Simplify.
Recall the formula for finding the circumference of a circle:
We can substitute in the value for the radius in order to find the circumference of the circle in question.
Solve.
Simplify.
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Find the circumference of a circle with a radius of 
.
Find the circumference of a circle with a radius of
Recall the formula for finding the circumference of a circle:
We can substitute in the value for the radius in order to find the circumference of the circle in question.
Solve.
Simplify.
Recall the formula for finding the circumference of a circle:
We can substitute in the value for the radius in order to find the circumference of the circle in question.
Solve.
Simplify.
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