Calculate the radius of gyration of a circular disc about its diameter.

Explanation

To calculate the radius of gyration of a circular disc about its diameter, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept**: The radius of gyration (k) is defined as the distance from the axis of rotation at which the entire mass of the body can be assumed to be concentrated without changing its moment of inertia.

2. **Moment of Inertia of the Disc**: The moment of inertia (I) of a circular disc about its diameter is given by the formula:
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