`ABCD` is such a quadrilateral that A is the centre of the circle passing through `B, C and D`. Prove that `/_CBD+ /_CDB =1/2 /_BAD`.

Explanation

To prove that \( \angle CBD + \angle CDB = \frac{1}{2} \angle BAD \) in quadrilateral \( ABCD \) where \( A \) is the center of the circle passing through points \( B, C, \) and \( D \), we can follow these steps:

### Step-by-Step Solution:

1. **Draw the Circle and the Quadrilateral:**
- Draw a circle with center \( A \) that passes through points \( B, C, \) and \( D \). Mark the points \( A, B, C, \) and \( D \) clearly.

2. **Identify Angles:**
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