Two light beams fall on a transparent material block at point 1 and 2 with angle respectively, as shown in figure. After refraction

Two light beams fall on a transparent material block at point 1 and 2 with angle 1 and 2 , respectively, as shown in figure. After refraction,
the beams intersect at point 3 which is exactly on the interface at other end of the block. Given : the distance between 1 and 2,

and

  , where refractive index of the block n2 > refractive index of the outside medium n1 , then the thickness of the block is ________ cm. 

                                                                          (JEE-2025)