The number of diagonals of a pentagon is

Options

A. 3
B. 4
C. 5
D. 10

Answer

To find the number of diagonals in a pentagon, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the number of sides in a pentagon**:
A pentagon has 5 sides.
\[ n = 5 \]

2. **Use the formula for the number of diagonals**:
The formula to calculate the number of diagonals \(D\) in a polygon with \(n\) sides is:
\[ D = \frac{n(n - 3)}{2} \]

3. **Substitute the value of \(n\)**:
Now, substitute \(n = 5\) into the formula:
\[ D = \frac{5(5 - 3)}{2} \]

4. **Simplify the expression**:
First, calculate \(5 - 3\):
\[ D = \frac{5 \times 2}{2} \]
Then, multiply:
\[ D = \frac{10}{2} \]

5. **Calculate the final result**:
Finally, divide:
\[ D = 5 \]

### Conclusion:
The number of diagonals in a pentagon is **5**.