Solve the given problem:
Problem: Calculate the angular displacement associated with the first order (m=1) diffraction pattern for visible light if the slit density is 8000 lines/cm. Do not assume the small angle approximation, since you are dealing with a multiple slit grating. Wavelength range for visible light is 400 nm to 700 nm.
I don't understand how to get the answer. Can you please help me with this problem?