The circumference of circle whose radius is 105 cm is _____

Options

A. 660 cm
B. 110 cm
C. 650 cm
D. 440 cm

Answer

To find the circumference of a circle given its radius, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the formula for circumference**:
The formula for the circumference \( C \) of a circle is given by:
\[ C = 2 \pi r \]
where \( r \) is the radius of the circle.

2. **Substitute the given radius**:
We are given that the radius \( r = 105 \) cm. Now, substituting this value into the formula:
\[ C = 2 \pi (105) \]

3. **Use the value of \( \pi \)**:
For this calculation, we can use the approximation \( \pi \approx \frac{22}{7} \). Therefore, we substitute \( \pi \) in the equation:
\[ C = 2 \times \frac{22}{7} \times 105 \]

4. **Calculate the multiplication**:
First, calculate \( 2 \times \frac{22}{7} \):
\[ C = \frac{44}{7} \times 105 \]

5. **Simplify the calculation**:
To simplify \( \frac{44 \times 105}{7} \), we can divide \( 105 \) by \( 7 \):
\[ 105 \div 7 = 15 \]
Now substitute back:
\[ C = 44 \times 15 \]

6. **Final multiplication**:
Now calculate \( 44 \times 15 \):
\[ C = 660 \text{ cm} \]

### Final Answer:
The circumference of the circle whose radius is 105 cm is **660 cm**.

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