Finding the Area of the Sector

Oct 13, 2025 by wbrum.org 61 views

Understanding the Problem

To find the approximate area of a sector, we need to use the formula for the area of a sector of a circle, which is given by:

${ A = \frac{\theta}{360} \pi r^2 }$

where $A$ is the area of the sector, $\theta$ is the central angle in degrees, and $r$ is the radius of the circle.

Given Information

We are given that the central angle $\Theta$ is approximately $92^\circ$ and the diameter of the circle is $9 \, \text{m}$ . We need to find the approximate area of the sector.

Finding the Radius

The radius of the circle is half of the diameter, so we can find the radius by dividing the diameter by 2:

${ r = \frac{9}{2} = 4.5 \, \text{m} }$

Finding the Area of the Sector

Now we can use the formula for the area of a sector to find the approximate area of the sector:

${ A = \frac{\theta}{360} \pi r^2 }$

Substituting the values of $\theta$ and $r$ , we get:

${ A = \frac{92}{360} \pi (4.5)^2 }$

Calculating the Area

To calculate the area, we need to evaluate the expression:

${ A = \frac{92}{360} \pi (4.5)^2 }$

${ A = \frac{92}{360} \pi (20.25) }$

${ A = \frac{92}{360} \times 20.25 \times \pi }$

${ A = \frac{92}{360} \times 63.55 }$

${ A = 0.255 \times 63.55 }$

${ A = 16.2 }$

Conclusion

Therefore, the approximate area of the sector is $16.2 \, \text{m}^2$ .

Comparison with Options

Comparing our result with the given options, we can see that the correct answer is:

D. $16.2 \, \text{m}^2$

Importance of Approximation

In this problem, we used an approximation for the value of $\pi$ and also approximated the value of the central angle $\Theta$ . This is because we are dealing with a real-world problem and we need to use approximate values to get an approximate answer.

Real-World Applications

The formula for the area of a sector of a circle has many real-world applications, such as:

Architecture: When designing buildings, architects need to calculate the area of sectors of circles to determine the size of windows, doors, and other architectural features.
Engineering: Engineers use the formula for the area of a sector to calculate the area of gears, pulleys, and other mechanical components.
Science: Scientists use the formula for the area of a sector to calculate the area of circular objects in scientific experiments.

Limitations of Approximation

While approximation is useful in many real-world problems, it also has its limitations. For example, if we need to calculate the area of a sector with high precision, we may need to use more precise values for $\pi$ and $\Theta$ .

Conclusion

In conclusion, the approximate area of a sector given $\Theta \approx 92^\circ$ with a diameter of $9 \, \text{m}$ is $16.2 \, \text{m}^2$ . This problem demonstrates the importance of approximation in real-world problems and the need to use precise values when high precision is required.

Q: What is the formula for the area of a sector of a circle?

A: The formula for the area of a sector of a circle is:

${ A = \frac{\theta}{360} \pi r^2 }$

where $A$ is the area of the sector, $\theta$ is the central angle in degrees, and $r$ is the radius of the circle.

Q: What is the central angle in a sector?

A: The central angle in a sector is the angle formed by two radii of the circle that intersect at the center of the circle.

Q: How do I find the radius of a circle?

A: To find the radius of a circle, you need to know the diameter of the circle. The radius is half of the diameter.

Q: What is the difference between a sector and a segment of a circle?

A: A sector is a region of a circle bounded by two radii and an arc, while a segment is a region of a circle bounded by a chord and an arc.

Q: Can I use the formula for the area of a sector to find the area of a full circle?

A: Yes, you can use the formula for the area of a sector to find the area of a full circle by setting the central angle to 360 degrees.

Q: What is the relationship between the area of a sector and the area of a full circle?

A: The area of a sector is a fraction of the area of a full circle, where the fraction is equal to the ratio of the central angle to 360 degrees.

Q: Can I use the formula for the area of a sector to find the length of an arc?

A: Yes, you can use the formula for the area of a sector to find the length of an arc by using the formula:

${ L = \frac{\theta}{360} 2\pi r }$

Q: What is the relationship between the length of an arc and the circumference of a circle?

A: The length of an arc is a fraction of the circumference of a circle, where the fraction is equal to the ratio of the central angle to 360 degrees.

Q: Can I use the formula for the area of a sector to find the area of a circular ring?

A: Yes, you can use the formula for the area of a sector to find the area of a circular ring by subtracting the area of the inner circle from the area of the outer circle.

Q: What is the relationship between the area of a circular ring and the area of a full circle?

A: The area of a circular ring is the difference between the area of the outer circle and the area of the inner circle.

Q: Can I use the formula for the area of a sector to find the volume of a spherical cap?

A: Yes, you can use the formula for the area of a sector to find the volume of a spherical cap by using the formula:

${ V = \frac{1}{3} \pi r^2 h }$

where $V$ is the volume of the spherical cap, $r$ is the radius of the base of the cap, and $h$ is the height of the cap.

Q: What is the relationship between the volume of a spherical cap and the volume of a full sphere?

A: The volume of a spherical cap is a fraction of the volume of a full sphere, where the fraction is equal to the ratio of the height of the cap to the radius of the sphere.

Conclusion

In conclusion, the formula for the area of a sector of a circle is a powerful tool for calculating the area of a sector, the length of an arc, and the volume of a spherical cap. By understanding the relationship between the area of a sector and the area of a full circle, you can use this formula to solve a wide range of problems in mathematics, science, and engineering.