In Fig. 12.30, OACB is a quadrant of a circle with centre O and radius 3.5 cm. If `O D=2c m`, find the area of the
(i) quadrant OACB,
(ii) shaded region.

Explanation

To solve the problem, we need to find the area of the quadrant OACB and the shaded region. Let's break it down step by step.

### Step 1: Find the area of the quadrant OACB

1. **Identify the radius (R)**: The radius of the quadrant is given as 3.5 cm.
2. **Convert the radius to a fraction**:
\[
R = 3.5 \text{ cm} = \frac{7}{2} \text{ cm}
...