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Problem 1 :
A cylindrical tank has radius 1.5 m. What is the circumference of its base ?
A cylindrical tank has the base which is in the shape of circle.
Circumference of base = 2πr
radius (r) = 1.5 m
Circumference of the base = 2(3.14)(1.5)
= 9.42 m 2
So, circumference of the base is 9.42 m 2 .
Problem 2 :
A circular pond has diameter 8 m and needs to be fenced for the protection of children.
a) What length of fencing is required?
b) Fencing comes in 1 m lengths. How many lengths are needed?
c) What is the total cost of the fencing if each length costs $25.00?
Diameter of the circular pond = 8 m, radius = 4 m
(a) Length of fencing = Circumference of circle
= 2 πr
= 2(3.14) (4)
= 25.12
So, length of fencing is 25.12 m.
(b) Length of each fencing = 1 m
Number of fencing required = 26
(c) Cost of each fencing = $25
Required cost = 25 (26)
= $650
So, the required cost is $650.
Problem 3 :
A car wheel has a radius of 35 cm.
a) What is the circumference of the wheel?
b) If the wheel rotates 100 000 times, how far does the car travel?
Radius of wheel = 35 cm
Circumference of the wheel = 2 πr
= 2(3.14) (35)
= 219.8
So, circumference of the circle is 220 cm.
(b) Distance covered in 100 000 times
= 100000(220)
= 22000000 cm
100 cm = 1 m and 1000 m = 1 km
= 22000000/100000
= 220 km
So, distance covered by the car is 220 km.
Problem 4 :
A trundle wheel is used for measuring distances. The circumference of the wheel is exactly 1 m. Each time the wheel rotates through one complete turn a click sound is heard and a counter adds a meter to the total. What is the radius of this wheel?
Circumference of circle = 1 m
2 πr = 1
2(3.14) r = 1
6.28r = 1
r = 1/6.28
r = 0.159 m
100 cm = 1 m and 1 cm = 10 mm
r = 159 mm
So, the required radius is 159 mm.
Problem 5 :
A circular garden plot has circumference 12.65 m. Find its radius in meters, correct to the nearest centimetre.
Circumference of circular garden = 12.65 m
2 πr = 12.65
2(3.14)r = 12.65
r = 12.65/6.28
r = 2.01 m
So, radius of the circular garden is 2.01 m.
Problem 6 :
An irrigation sprinkler sprays water over a field. The radius of the spray is 12.6 m. What area of the field is being watered?
Radius of the spray = 12.6 m
Area of the field is being watered = Area of circle
= πr 2
= 3.14(12.6) 2
= 3.14(158.76)
= 498.50
So, area of the field is being watered is 498.50 m 2
Problem 7 :
The rope connecting a goat to a pole is 8 m long. What area of grass can the goat eat?
Length of rope = 8 m
Area of grass can the goat eat = πr 2
= 3.14(8) 2
= 200.96
= 201 m 2
So, area of grass can the goat eat is 201 m 2 .
Problem 8 :
A circular hoop has a radius of 40 cm. Find the length of tubing needed to make the hoop.
Radius of circular hoop = 40 cm
Length of tubing needed to make a hoop = 2 πr
= 2(3.14)(40)
= 251.2
So, length of tubing needed is 251.2 cm.
Problem 9 :
6 identical metal discs are stamped out of an 18 cm by 12 cm sheet of copper as illustrated. What percentage of the copper is wasted
Area of 6 stamps = 6 πr 2
3(diameter of circle) = 18
3(2r) = 18
r = 18/6
r = 3 cm
Area = 6(3.14)(9)
Area of metal discs cut out = 169.56 cm 2
Copper wasted = Area of rectangular sheet - Area of metal discs cut out
= 18 x 12 - 169.56
= 216-56.52
= 46.44
= (46.44/216) ⋅ 100%
= 21.5%
So, copper wasted is 21.5%.
Problem 10 :
A table-top is shaped as illustrated. A cloth to protect the table-top from stains and heat is cut exactly the same size as the table-top. It is made from fabric 1.6 m wide and costs $18.40 per metre of length.
a) What length of fabric must be purchased?
b) Calculate the cost of the fabric.
c) Find the area of the cloth.
d) Calculate the amount of fabric that is wasted.
(a) Length of fabric to be purchased = Side length of one side
= 2.4 + 0.8 + 0.8
= 4 m
So, length of fabric to be purchased is 4 m.
(b) Cost of fabric = $18.40
Cost of fabric purchased = 18.40(4)
= $73.60
(c) Area of cloth
= Area of rectangle in the middle + 2(Area of semicircle)
= 2.4(1.6) + 2( πr 2 /2)
= 3.84 + (3.14)(0.8) 2
= 3.84 + 2.0096
= 5.85 m 2
d) Amount of fabric wasted = (2.4+16) x 1.6 - 2.0096
= 6.4 - 5.85
= 0.55 m 2
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Area of a circle – formula and examples.
The area of a circle can be thought of as the number of square units of space the circle occupies. This can be found using either the radius or the diameter, which we will cover in the examples below. We will also look at some examples of word problems involving area that you may come across in your studies. [adsenseWide]
We will use the following formula to find the area of any circle. Notice that this formula uses the radius, so we will have to convert when we are given the diameter instead. Let’s look at both cases.
Find the area of a circle with a radius of 5 meters.
Apply the formula: \(A = \pi r^2\) with radius \(r = 5\). Remember that \(\pi\) is about 3.14.
\(\begin{align}A &= \pi (5)^2 \\ &= 25\pi \\ &\approx \bbox[border: 1px solid black; padding: 2px]{75.5 \text{ m}^2}\end{align}\)
A few comments about this final answer.
Since the units of the radius were in meters, the answer is in square meters. This can be written out in words, or as \(\text{m}^2\). Also, the final answer can be written in terms of \(\pi\) (\(25 \pi\) square meters) or as a decimal approximation (75.5 square meters). Which one you use depends on the application and the problem you are working on.
Find the area of a circle with a diameter of 6 feet.
The radius of any circle is always half the diameter. Since the diameter of the circle is 6 feet, the radius must be 3 feet (the radius is always half of the diameter). So, we can apply the formula using \(r = 3\).
\(\begin{align}A &= \pi (3)^2 \\ &= 9\pi \\ &\approx \bbox[border: 1px solid black; padding: 2px]{28.3 \text{ ft}^2}\end{align}\)
As you can see, it is important to pay attention to whether or not you are given the radius or the diameter of the circle. In some word problems though, this may not always be as clear.
Not every problem you will encounter will simply say “find the area”. In the next two examples, you will see other types of questions you might be asked.
Jason is painting a large circle on one wall of his new apartment. The largest distance across the circle will be 8 feet. Approximately how many square feet of wall will the circle cover?
Whenever you are asked to find the number of square feet covered by something, you are finding an area. To find the area of Jason’s circle, we first need to figure out if we have been given the radius or the diameter. By definition, the diameter of a circle is the longest distance across the circle, so we know here that the diameter is 8 feet. This means that the radius is 4 feet. Therefore:
\(\begin{align}A &= \pi (4)^2 \\ &= 16\pi \\ &\approx \bbox[border: 1px solid black; padding: 2px]{50.2 \text{ square feet}}\end{align}\)
So, Jason’s circle will cover about 50.2 square feet of his wall.
The area of a circle is \(81 \pi\) square units. What is the radius of this circle?
To answer this question, you will have to remember a little bit of algebra. Use the formula and substitute the values you know. Then, solve for the radius, \(r\).
Start with the area formula.
\(A = \pi r^2\)
Substitute in \(A = 81 \pi\) since you know this is the area.
\(81\pi = \pi r^2\)
Divide both sides by \(\pi\).
\(81 = r^2\)
This can also be written as:
\(r^2 = 81\)
Take the square root to find \(r\). Since this is a radius, the value of \(r\) must be positive.
\(\begin{align}r &= \sqrt{81} \\ &= \bbox[border: 1px solid black; padding: 2px]{9}\end{align}\)
Therefore, the radius must be 9.
[adsenseLargeRectangle]
Finding the area of a circle is all about applying the formula. But be careful! You always must pay attention to the information you are given – especially in applied problems.
Answer & Explanation
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Exploring the nature of diversity dishonesty within predominantly white schools of medicine, pharmacy, and public health at the most highly selective and highly ranked u.s. universities.
Burrell, D.N. Exploring the Nature of Diversity Dishonesty within Predominantly White Schools of Medicine, Pharmacy, and Public Health at the Most Highly Selective and Highly Ranked U.S. Universities. Soc. Sci. 2024 , 13 , 332. https://doi.org/10.3390/socsci13070332
Burrell DN. Exploring the Nature of Diversity Dishonesty within Predominantly White Schools of Medicine, Pharmacy, and Public Health at the Most Highly Selective and Highly Ranked U.S. Universities. Social Sciences . 2024; 13(7):332. https://doi.org/10.3390/socsci13070332
Burrell, Darrell Norman. 2024. "Exploring the Nature of Diversity Dishonesty within Predominantly White Schools of Medicine, Pharmacy, and Public Health at the Most Highly Selective and Highly Ranked U.S. Universities" Social Sciences 13, no. 7: 332. https://doi.org/10.3390/socsci13070332
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Area of a Circle Practice Problems with Answers. There are twelve (12) practice problems in this exercise about the area of the circle. You may use a calculator. Do not round intermediate calculations. Round your final answer to two decimal places unless the exact answer is required.
The Corbettmaths Practice Questions on the Area of a Circle. Welcome; Videos and Worksheets; Primary; 5-a-day. 5-a-day GCSE 9-1; 5-a-day Primary; 5-a-day Further Maths ... Click here for Questions. Click here for Answers. circles. Practice Questions. Previous: Arc Length Practice Questions. Next: Area of a Sector Practice Questions. GCSE ...
The other way to solve this problem is to divide the diameter by 2 to get the radius and follow the regular area of the circle formula with radius. Question 2: Find the area of the circle whose radius is 32 units. Solution: Given the radius is 32 units. Area of circle = πr2. = 22/7 × 32 × 32. = (22 × 32 × 32 ) / 7.
Find the area of a circle with a circumference of 12.56 units. units 2. Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.
Example 1 : calculating the area of the circle given the radius. A circle has a radius of 6\mathrm {~cm}. 6 cm. Calculate its area. Give your answer to 2 \text { dp}. 2 dp. Find the radius of the circle. The length of the radius is given in the question, r=6\mathrm {~cm}. r = 6 cm.
Calculate the area of the shaded region. Give your answer to 2 decimal places. 6. A circular flower bed has diameter 7 metres. Work out the area of the flower bed. Give your answer correct to 1 decimal place. 7. Shown below is a circular photo surrounded by a frame. The photo has radius 12cm.
So, the area of a circle with a diameter of 63 cm is 3118.5 square cm. Remember, you can also find the radius by dividing the diameter by 2 and use the formula πr 2 to solve this problem. Question 2: What is the area of a circle with a radius of 32 units? Solution:
Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. ... Area and circumference challenge problems. Finding circumference of a circle when given the area. ... Finding circumference of a circle when given the area . Video 1 minute 31 seconds 1:31. Area of a shaded ...
Practice Finding the Area of a Circle with practice problems and explanations. Get instant feedback, extra help and step-by-step explanations. Boost your Algebra grade with Finding the Area of a ...
To find the area of a circle, we need to find the radius first. The radius of the circle is half of the diamter which is half of 7 = 3.5 inches. Next we need to square the radius: 3.5 2 = 3.5 x 3.5 = 12.25 cm. Finally we need to multiply this amount by pi (π). So the area of this circle is π x r 2 = π x 12.25 cm.
Find the area the circle with a diameter of 10 inches. Solution: Step 1: Write down the formula: A = πr 2. Step 2: Change diameter to radius: Step 3: Plug in the value: A = π5 2 = 25π. Answer: The area of the circle is 25π ≈ 78.55 square inches. Example 2:
A circle has a radius of 6cm 6cm, calculate its area. Give your answer to 2dp 2dp. Find the radius of the circle. The radius is given in the question. Radius =6cm = 6cm. 2 Use the formula \pi r^2 πr2 to calculate the area of the circle. \begin {aligned} &\pi r^2\\\\ &= \pi \times r\times r\\\\ &= \pi \times6\times 6\\\\ &= 36\pi \\\\ &= 113. ...
Since we have that the diameter is 3 m, we divide it by 2 to get the radius which then is 1.5 m. Plugging values into the equation, we have: A = π (3 / 2 m)) 2. A = π (2.25 m 2) A = 2.25π m 2. Complexity=4, Mode=fraction. Find the area. Use 22/7 as an approximation for π, but give the final answer in decimal.
Area, circumference, diameter and radius. Area and circumference both relate to the radius and diameter of a circle. Once you know one, you can find all of the others -- It just takes a little math!
Solved Problems on Circle. Let us understand the concepts related to circles along with the following questions-. Example 1: To cover a distance of 10 km, a wheel rotates 5000 times. Find the radius of the wheel. Solution: Number of rotations = 5000. Total distance covered = 10 km. Let 'r' be the radius of the wheel.
MATH MONKS 1 Word Problems Area and Circumference of a Circle - Answers Sohan purchased a wall clock. The radius of the clock is 20 cm. What is the area and circumference of the wall clock ? Area = 1256.63 cm2, Circumference = 125.66 cm Pamela bought a new Fiat- four wheeler car. The radius of the wheel is 36 in. Find the
Click here for Questions. Circles. Textbook Exercise. Previous: Area of Compound Shapes Textbook Exercise. Next: Types of Angles Textbook Exercise. The Corbettmaths Textbook Exercise on the Area of Circles.
Circle Worksheets. This generator makes worksheets for calculating the radius, diameter, circumference, or area of a circle, when one of those is given (either radius, diameter, circumference, or area is given). They can be made in PDF or html formats. Options are numerous: you can choose metric or customary units or both, you can include or ...
The area of a circle is size of the surface of the circle. The formula is πr 2. The area of the circle is expressed in square units. Since the formula is only given in terms of radius, remember to change from diameter to radius when necessary. Read the lesson on area of circle if you need to learn how to calculate the area of a circle.
Area of a Circle (with detailed solutions) Two worksheets focusing on finding areas of circles and circular shapes. Problem-type questions are included as well. I find that these sheets are very useful as homework tasks for Y8 and older. As an extra, I have included a NEW STYLE of PowerPoint, which allows questions and solutions to be easily ...
Area of the field is being watered = Area of circle = πr 2 = 3.14(12.6) 2 = 3.14(158.76) = 498.50. So, area of the field is being watered is 498.50 m 2. Problem 7 : The rope connecting a goat to a pole is 8 m long. What area of grass can the goat eat? Solution : Length of rope = 8 m. Area of grass can the goat eat = πr 2 = 3.14(8) 2
Word problems involving the area of a circle. Not every problem you will encounter will simply say "find the area". In the next two examples, you will see other types of questions you might be asked. Example. Jason is painting a large circle on one wall of his new apartment. The largest distance across the circle will be 8 feet.
A semicircle having centre at O and radius equal to 4 is drawn with PQ as the diameter as shown is the figure given below. OSRU is a rectangle such that the ratio of area of the semicircle to the area of the rectangle is 2π: 3 or cuts the semicircle at T. Find the length of line segment TQ. A. (8/5)√5. B. (5/3)√5. C. (17/9)√5. D. (9/2)√5.
Recognizing the critical need to address diversity dishonesty, this article comprehensively explores frameworks to understand and combat this phenomenon. It seeks to engage with viable theories, problem-solving approaches, and contextual models that can illuminate the complex interplay of factors contributing to diversity dishonesty.