Find the area of a circle whose radius is
Q(i) 21 cm.
(ii)3.5m

Answer

To find the area of a circle, we use the formula:

\[ \text{Area} = \pi r^2 \]

where \( r \) is the radius of the circle.

### Solution for (i) Radius = 21 cm

1. **Identify the radius**: The radius \( r = 21 \) cm.
2. **Substitute the radius into the area formula**:
\[ \text{Area} = \pi (21)^2 \]
3. **Calculate \( (21)^2 \)**:
\[ (21)^2 = 441 \]
4. **Substitute the value of \( (21)^2 \) back into the area formula**:
\[ \text{Area} = \pi \times 441 \]
5. **Use \( \pi \approx \frac{22}{7} \)**:
\[ \text{Area} = \frac{22}{7} \times 441 \]
6. **Multiply \( 22 \) by \( 441 \)**:
\[ 22 \times 441 = 9702 \]
7. **Divide by \( 7 \)**:
\[ \text{Area} = \frac{9702}{7} = 1386 \text{ cm}^2 \]

### Solution for (ii) Radius = 3.5 m

1. **Identify the radius**: The radius \( r = 3.5 \) m.
2. **Substitute the radius into the area formula**:
\[ \text{Area} = \pi (3.5)^2 \]
3. **Calculate \( (3.5)^2 \)**:
\[ (3.5)^2 = 12.25 \]
4. **Substitute the value of \( (3.5)^2 \) back into the area formula**:
\[ \text{Area} = \pi \times 12.25 \]
5. **Use \( \pi \approx \frac{22}{7} \)**:
\[ \text{Area} = \frac{22}{7} \times 12.25 \]
6. **Convert \( 12.25 \) to a fraction**:
\[ 12.25 = \frac{1225}{100} = \frac{49}{4} \]
7. **Multiply**:
\[ \text{Area} = \frac{22}{7} \times \frac{49}{4} = \frac{1078}{28} = 38.5 \text{ m}^2 \]

### Final Answers:
(i) Area of the circle with radius 21 cm = **1386 cm²**
(ii) Area of the circle with radius 3.5 m = **38.5 m²**