Answer:
28.82°
Explanation:
the equation for a diffraction grating is given by
[tex]dsin\theta=m\lambda[/tex]
where d is the distance between slits, m is the order of the bright fringe and lambda is the wavelength of the light. By replacing we obtain:
[tex]sin\theta=\frac{m\lambda}{d}=\frac{(3)(656nm)}{4082nm}=0.482\\\\\theta=sin^{-1}(0.482)=28.82\°[/tex]
Then, for the third fringe the angle is 28.82°.
hope this helps!!