In Fig. 12.31, a square OABC is inscribed in a quadrant OPBQ. If `O A=20 c m ,`find the area of the shaded region. (`U s e pi=3. 14`)

Explanation

To solve the problem of finding the area of the shaded region in the figure with a square OABC inscribed in a quadrant OPBQ, we can follow these steps:

### Step 1: Find the area of the square OABC.
Given that the side of the square OA = 20 cm, we can calculate the area of the square using the formula:

\[ \text{Area of square} = \text{side}^2 = OA^2 = 20^2 = 400 \text{ cm}^2 \]
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