The height of a circular cylinder is 20 cm and the radius of its base is 7 cm. Find :
the volume

Answer

To find the volume of a circular cylinder, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the given values**:
- Height (H) of the cylinder = 20 cm
- Radius (R) of the base = 7 cm

2. **Write the formula for the volume of a cylinder**:
The volume \( V \) of a cylinder is given by the formula:
\[ V = \pi r^2 h \]
where \( r \) is the radius and \( h \) is the height.

3. **Substitute the values into the formula**:
Here, we will use \( \pi \approx \frac{22}{7} \) for calculation.
\[ V = \pi \times (7 \, \text{cm})^2 \times (20 \, \text{cm}) \]

4. **Calculate \( r^2 \)**:
\[ (7 \, \text{cm})^2 = 49 \, \text{cm}^2 \]

5. **Substitute \( r^2 \) back into the volume formula**:
\[ V = \frac{22}{7} \times 49 \, \text{cm}^2 \times 20 \, \text{cm} \]

6. **Simplify the expression**:
- First, simplify \( \frac{49}{7} \):
\[ \frac{49}{7} = 7 \]
- Now substitute back:
\[ V = 22 \times 7 \, \text{cm}^2 \times 20 \, \text{cm} \]

7. **Calculate \( 22 \times 7 \times 20 \)**:
- First calculate \( 22 \times 7 = 154 \)
- Then multiply by 20:
\[ 154 \times 20 = 3080 \, \text{cm}^3 \]

8. **Final answer**:
The volume of the cylinder is:
\[ V = 3080 \, \text{cm}^3 \]