If in a `triangle ABC` , a = 6 , b = 3 and cos (A -B) =`4/5`,then its area in square units, is

Options

A. 8
B. 9
C. 6
D. none of these

Explanation

To find the area of triangle ABC given that \( a = 6 \), \( b = 3 \), and \( \cos(A - B) = \frac{4}{5} \), we can follow these steps:

### Step-by-Step Solution:

1. **Use the Cosine Difference Identity**:
We know that:
\[
\cos(A - B) = \frac{4}{5}
...