`A B C D` is a rhombus. If `/_A C B=40^@,` find `/_A D Bdot`

Explanation

To solve the problem, we need to find the angle \( \angle ADB \) in the rhombus \( ABCD \) given that \( \angle ACB = 40^\circ \).

### Step-by-Step Solution:

1. **Understand the Properties of a Rhombus**:
- In a rhombus, the diagonals bisect each other at right angles. This means that \( \angle AOB = 90^\circ \) where \( O \) is the intersection point of the diagonals \( AC \) and \( BD \).

2. **Identify the Angles in Triangle \( ACB \)**:
...