In the figure O is the centre of the circle and A, B, C are points on the circle. AOB = 50^, BOC = 80^. 
\( z_1, z_2, z_3 \) represent the vertices A, B, C of a triangle ABC respectively in the Argand plane. If
\[ |z_1 - z_2| = \sqrt{25 - 12 \sqrt{3}}, \] \[ \left|\frac{z_1 - z_3}{z_2 - z_3}\right| = \frac{3}{4}, \] \[ \text{and } \angle ACB = 30^\circ, \]
Then the area (in sq. units) of that triangle is: