Opposite angles of a quadrilateral ABCD are equal. If AB = 4 cm, determine CD.

Explanation

To solve the problem, we need to use the property of a quadrilateral where opposite angles are equal. Let's break down the solution step by step.

### Step-by-Step Solution:

1. **Understanding the Property**: In a quadrilateral where opposite angles are equal, it can be inferred that the quadrilateral is a special type of quadrilateral, specifically a parallelogram. In a parallelogram, opposite sides are also equal.

2. **Identifying the Sides**: We are given that one of the sides, AB, is 4 cm. Since opposite sides are equal in a parallelogram, we can denote the sides as follows:
- AB = CD
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