Find the circumference of a circle whose radius is
(i) 28 cm
(ii) 1.4 m.

Answer

To find the circumference of a circle given its radius, we can use the formula:

**Circumference (C) = 2 × π × r**

Where:
- C is the circumference,
- π (pi) is approximately 22/7 or 3.14,
- r is the radius of the circle.

Now, let's solve the problem step by step for both cases.

### Step 1: Find the Circumference for Radius 28 cm

1. **Identify the radius**:
- Given radius (r) = 28 cm.

2. **Use the formula for circumference**:
- C = 2 × π × r
- Substitute π with 22/7:
- C = 2 × (22/7) × 28

3. **Calculate the multiplication**:
- First, calculate 2 × 22 = 44.
- Now, multiply 44 by 28:
- 44 × 28 = 1232.

4. **Divide by 7**:
- C = 1232 / 7 = 176 cm.

### Step 2: Find the Circumference for Radius 1.4 m

1. **Identify the radius**:
- Given radius (r) = 1.4 m.

2. **Convert 1.4 m to cm for consistency**:
- 1.4 m = 140 cm.

3. **Use the formula for circumference**:
- C = 2 × π × r
- Substitute π with 22/7:
- C = 2 × (22/7) × 140

4. **Calculate the multiplication**:
- First, calculate 2 × 22 = 44.
- Now, multiply 44 by 140:
- 44 × 140 = 6160.

5. **Divide by 7**:
- C = 6160 / 7 = 880 cm.

6. **Convert back to meters**:
- Since 100 cm = 1 m,
- C = 880 cm = 8.8 m.

### Final Answers:
- Circumference for radius 28 cm = **176 cm**.
- Circumference for radius 1.4 m = **8.8 m**.