Calculating Radius for Given Diameter

Oct 13, 2025 by wbrum.org 46 views

Introduction

In geometry, a circle is a set of points that are all equidistant from a central point called the center. The distance from the center to any point on the circle is called the radius. The diameter of a circle is the distance across the circle passing through its center. In this article, we will discuss how to calculate the radius for a given diameter in different cases and also learn how to draw circles.

What is Radius and Diameter?

The radius of a circle is the distance from the center of the circle to any point on the circle. It is denoted by the letter 'r'. The diameter of a circle is the distance across the circle passing through its center. It is denoted by the letter 'd'. The relationship between the radius and diameter is given by the formula:

d = 2r

Calculating Radius for Given Diameter

To calculate the radius for a given diameter, we can use the formula:

r = d/2

This formula can be used to calculate the radius for any given diameter.

Case 1: Calculating Radius for a Given Diameter

Suppose we are given a diameter of 10 cm. We can calculate the radius using the formula:

r = d/2 = 10/2 = 5 cm

So, the radius of the circle is 5 cm.

Case 2: Calculating Radius for a Given Diameter in Decimal Form

Suppose we are given a diameter of 10.5 cm. We can calculate the radius using the formula:

r = d/2 = 10.5/2 = 5.25 cm

So, the radius of the circle is 5.25 cm.

Case 3: Calculating Radius for a Given Diameter in Fractional Form

Suppose we are given a diameter of 3/2 cm. We can calculate the radius using the formula:

r = d/2 = (3/2)/2 = 3/4 cm

So, the radius of the circle is 3/4 cm.

Drawing Circles

To draw a circle, we need to use a compass or a circular object. Here are the steps to draw a circle:

Place the point of the compass on the center of the circle.
Open the compass to the desired radius.
Draw a circle by moving the compass around the center point.

Drawing a Circle with a Given Diameter

To draw a circle with a given diameter, we can use the following steps:

Place the point of the compass on the center of the circle.
Open the compass to half of the given diameter.
Draw a circle by moving the compass around the center point.

Example: Drawing a Circle with a Diameter of 10 cm

To draw a circle with a diameter of 10 cm, we can use the following steps:

Place the point of the compass on the center of the circle.
Open the compass to 5 cm (half of the given diameter).
Draw a circle by moving the compass around the center point.

Conclusion

In this article, we discussed how to calculate the radius for a given diameter in different cases and also learned how to draw circles. We used the formula r = d/2 to calculate the radius for a given diameter and used a compass to draw a circle. We also learned how to draw a circle with a given diameter.

Frequently Asked Questions

Q: What is the relationship between the radius and diameter of a circle?

A: The relationship between the radius and diameter of a circle is given by the formula d = 2r.

Q: How can we calculate the radius for a given diameter?

A: We can calculate the radius for a given diameter using the formula r = d/2.

Q: How can we draw a circle with a given diameter?

A: We can draw a circle with a given diameter by using a compass and opening it to half of the given diameter.

Q: What is the center of a circle?

A: The center of a circle is the point from which the distance to any point on the circle is equal.

Q: What is the radius of a circle?

A: The radius of a circle is the distance from the center of the circle to any point on the circle.

Q: What is the diameter of a circle?

A: The diameter of a circle is the distance across the circle passing through its center.

References

[1] Geometry, by Michael Artin
[2] Calculus, by Michael Spivak
[3] Mathematics, by Richard Courant

Glossary

Radius: The distance from the center of a circle to any point on the circle.
Diameter: The distance across a circle passing through its center.
Center: The point from which the distance to any point on the circle is equal.
Compass: A circular object used to draw a circle.
Circle: A set of points that are all equidistant from a central point called the center.
Calculating Radius for Given Diameter and Drawing Circles: Q&A ================================================================

Introduction

In our previous article, we discussed how to calculate the radius for a given diameter in different cases and also learned how to draw circles. In this article, we will answer some frequently asked questions related to calculating radius for given diameter and drawing circles.

Q&A

Q: What is the formula to calculate the radius for a given diameter?

A: The formula to calculate the radius for a given diameter is r = d/2.

Q: How can we calculate the radius for a given diameter in decimal form?

A: We can calculate the radius for a given diameter in decimal form by using the formula r = d/2, where d is the given diameter in decimal form.

Q: How can we calculate the radius for a given diameter in fractional form?

A: We can calculate the radius for a given diameter in fractional form by using the formula r = d/2, where d is the given diameter in fractional form.

Q: What is the relationship between the radius and diameter of a circle?

A: The relationship between the radius and diameter of a circle is given by the formula d = 2r.

Q: How can we draw a circle with a given diameter?

A: We can draw a circle with a given diameter by using a compass and opening it to half of the given diameter.

Q: What is the center of a circle?

A: The center of a circle is the point from which the distance to any point on the circle is equal.

Q: What is the radius of a circle?

A: The radius of a circle is the distance from the center of the circle to any point on the circle.

Q: What is the diameter of a circle?

A: The diameter of a circle is the distance across the circle passing through its center.

Q: Can we calculate the radius for a negative diameter?

A: No, we cannot calculate the radius for a negative diameter. The diameter of a circle is always a positive value.

Q: Can we draw a circle with a negative diameter?

A: No, we cannot draw a circle with a negative diameter. The diameter of a circle is always a positive value.

Q: What is the unit of measurement for the radius and diameter of a circle?

A: The unit of measurement for the radius and diameter of a circle is the same as the unit of measurement for the given diameter.

Q: Can we calculate the radius for a diameter with a unit of measurement other than centimeters?

A: Yes, we can calculate the radius for a diameter with a unit of measurement other than centimeters. We just need to use the correct unit of measurement in the formula.

Q: Can we draw a circle with a diameter that has a unit of measurement other than centimeters?

A: Yes, we can draw a circle with a diameter that has a unit of measurement other than centimeters. We just need to use the correct unit of measurement in the compass.

Conclusion

In this article, we answered some frequently asked questions related to calculating radius for given diameter and drawing circles. We hope that this article has been helpful in clarifying any doubts that you may have had.

Frequently Asked Questions

Q: What is the relationship between the radius and diameter of a circle?

A: The relationship between the radius and diameter of a circle is given by the formula d = 2r.

Q: How can we calculate the radius for a given diameter?

A: We can calculate the radius for a given diameter using the formula r = d/2.

Q: How can we draw a circle with a given diameter?

A: We can draw a circle with a given diameter by using a compass and opening it to half of the given diameter.

Q: What is the center of a circle?

A: The center of a circle is the point from which the distance to any point on the circle is equal.

Q: What is the radius of a circle?

A: The radius of a circle is the distance from the center of the circle to any point on the circle.

Q: What is the diameter of a circle?

A: The diameter of a circle is the distance across the circle passing through its center.

References

[1] Geometry, by Michael Artin
[2] Calculus, by Michael Spivak
[3] Mathematics, by Richard Courant

Glossary

Radius: The distance from the center of a circle to any point on the circle.
Diameter: The distance across a circle passing through its center.
Center: The point from which the distance to any point on the circle is equal.
Compass: A circular object used to draw a circle.
Circle: A set of points that are all equidistant from a central point called the center.