In the Figure, `O D` is perpendicular to the chord `A B` of a circle whose centre is `O`. If `B C` is a diameter, show that `C A=2 OD`.

Explanation

To solve the problem, we need to show that \( CA = 2 \cdot OD \) given that \( OD \) is perpendicular to the chord \( AB \) and \( BC \) is a diameter of the circle.

### Step-by-Step Solution:

1. **Identify the Given Information**:
- \( O \) is the center of the circle.
- \( OD \) is perpendicular to the chord \( AB \).
- \( BC \) is a diameter of the circle.
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