Question

Diameter of a circle whose radius is 'r' will be :

• A. 3r
• B. 4r
• C. \( \frac{3}{2} \)r
• D. 2r

Hint:

Always remember the basic circle formulas: Diameter \(d = 2r\), Circumference \(C = 2\pi r\), and Area \(A = \pi r^2\). Knowing the relationship \(d=2r\) helps derive other formulas as well.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept
This question asks for the relationship between the diameter and the radius of a circle.
Step 2: Key Formula or Approach
The radius (r) is the distance from the center of the circle to any point on its circumference.
The diameter (d) is the distance across the circle passing through its center. The diameter is the longest chord of a circle.
The formula relating diameter and radius is:
\[ \text{Diameter} = 2 \times \text{Radius} \] \[ d = 2r \] Step 3: Detailed Explanation
Given that the radius is 'r', we apply the formula.
Diameter = 2 \( \times \) r = 2r.