I can't figure out what I am doing wrong!!! Getting Frustrated!! 1. The problem statement, all variables and given/known data A helium-neon laser (λ=629 nm) illuminates a diffraction grating. The distance between the two m=3 bright fringes is 33 cm on a screen 1.72 m behind the grating. What is the spacing between slits of the grating? 2. Relevant equations Lamda = 629 nm m = 3 y = 0.33 m L = 1.72 m d = ? 3. The attempt at a solution What I did was tan theta = y/L = 0.33/1.72 = 1086 degrees then I used the equation d*sin theta = m*lamda and solved for d.... d = m*lamda/sin theta = 1.00x10^-5 m but I am getting it wrong...what am I not doing right???