How to Find the Area of a Quadrant (a Quarter of a Circle)
A quadrant is a quarter of a circle. So to work out the area of a quadrant, first work out the area of the whole circle (use the formula A = π ×r²) and then divide the answer by 4. Alternatively, you could substitute the radius of the quadrant directly into the formula A = ¼ πr². Let’s take a look at a few examples on working out the area of quadrants:
Example 1
Work out the area of this quadrant (radius 8cm).
Method 1 (using the area of a whole circle and dividing by 4)
First work out the area of the whole circle by substituting the radius of 8cm into the formula for the area of the circle:
A = π ×r²
= π ×8²
= 64π (leave the answer as an exact solution as this need to be divided by 4).
So all you need to do now is divide the answer by 4:
Area of a quadrant = 64π ÷4 = 16π = 50.3 cm² to 3 significant figures.
Method 2 (using ¼ πr²)
Substitute r = 8 directly into the formula A = ¼ πr².
A = ¼ πr².
A = ¼ × π × 8².
A = 50.3 cm²
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As you can see it gives exactly the same answer as method 1.
Example 2
Work out the area of this quadrant (radius 3.8m).
Like example 1, begin by substituting the radius of 3.8m into the formula for the area of the circle:
A = π ×r²
= π ×3.8²
= 14.44π (leave the answer as an exact solution as this need to be divided by 4).
Again, all you need to do now is divide the answer by 4:
Area of a quadrant = 14.44π ÷4 = 16π = 11.3 m² to 3 significant figures.
Method 2
Substitute r = 3.8m directly into the formula A = ¼ πr².
A = ¼ πr².
A = ¼ × π × 3.8².
A = 11.3 m²
As you can see it gives exactly the same answer as method 1.
Questions & Answers
Question: Can you find the area of quadrant of a circle whose circumference is 22?
Answer: First, find the radius of the circle by dividing the circumfernece by Pi and halving the answer to give 3.501 to 3 decimal places.
Now use 0.25*Pi*radius^2 to give the area of the quadrant 0.25*Pi*3.501^2 = 9.63 to 2 decimal places.
Question: If the area of a circle is 100 cm2, what's the area of one of its quadrants?
Answer: All you need to do is divide 100 by 4 to give 25 cm^2.
Question: Can you find the area of a quadrant whose radius is 9cm?
Answer: Square 9 to give 81.
Now multiply 81 by 3.14 to give 254.34.
Finally divide 254.34 by 4 to give 63.6 to 1 decimal place.
Question: What is the area of the quadrant with a radius of 14cm ?
Answer: The area of the whole circle is Pi times 14 times 14 which gives 615.75... cm^2.
Now divide this answer by 4 to give 153.9 cm^2 to 1 decimal place (or 49Pi).
Question: What is the area of a quadrant with a radius of 6cm, given in terms of Pi?
Answer: First square the radius of 6 to give 36.
Now multiply 36 by Pi to give 36Pi
Next, divide the answer by 4 to 9Pi.
Question: What is the formula for working out the area of a quadrant?
Answer: 0.25*Pi*r^2.
Question: Is the area of a quarter-circle supposed to be (8² x π) /4 ?
Answer: Yes, the formula can be written as (radius² x π) /4.
I think you are showing an example when the radius of the quarter circle is 8.
Question: If the wheel of a gate is 3 feet from the wall and it turns over 90 degrees, what is the distance covered by the wheel?
Answer: First double 3 feet to give a diameter of 6 feet.
Next multiply 3.14 by 6 to give the circumference of the whole circle which is 18.84 feet.
Now divide the answer by 4 as 90 degrees is 1/4 of the whole circle to give 4.7 feet to 1 decimal place.
Question: What is the area of a quadrant with a radius of 4.3cm?
Answer: Work out 0.25 mutlplied by Pi multiplied by 4.3^2 to give 14.5 cm^2 rounded to 1 decimal place.
Question: What is the Area for 1/4 circle with radius of 6?
Answer: First square the radius to give 36, and multiply it by π to give 36π.
Now divide this answer by 4 to give 9π.
Question: The radius of a quarter circle is 3 millimeters. What is the quarter circle's area? (r=3 mm, Pi = 3.14)
Answer: Work out 3^2 which is 9.
Now times 9 by 3.14 which is 28.26.
Now divide 28.26 by 4 to give 7.065 mm^2.
Comments
d,annalee on September 08, 2013:
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