$\"\"$

Redraw the diagram :

$\"\"$

In the above diagram, three triagulars with same sides and angle.

Consider the $\"\"$ with sides of $\"\"$ and $\"\"$ .

The angle is $\"\"$ .

Therefore the area of triangle is , $\"\"$ .

$\"\"$

Therefore, the area of triangle is $\"\"$ .

$\"\"$

Observe the figure:

As the three triangles $\"\"$ , $\"\"$ and $\"\"$ are equal , the total area of triangle is the threee times of anyone of the triangle.

Therefore , total area is $\"\"$ .

Total area is $\"\"$ .

Hence total area is $\"\"$ .

$\"\"$

Total area is $\"\"$ .