Monochromatic light from a helium-neon laser is incident normally on a diffraction grating which has slit width (d) 1667 nm. The first-maximum order...

Monochromatic light from a helium-neon laser is incident normally on a diffraction grating which has slit width (d) 1667 nm. The first-maximum order (m = 1) is diffracted 22.31 deg. from the incident normal. What would be the wavelength of this monochromatic light? (in nanometer)