A diffraction grating is to be used to find the wavelength of the light in the emission spectrum of a gas. The grating spacing is not known, but a light having a known wavelength of 627.9 nm is deflected by 43.9° away from the central maximum in the second order by this grating. Light of the wavelength to be measured is deflected by 49° away from the central maximum in the second order. What is the wavelength of this light? (Give answer to the nearest nm)

Question

A diffraction grating is to be used to find the wavelength of the light in the emission spectrum of a gas. The grating spacing is not known, but a light having a known wavelength of 627.9 nm is deflected by 43.9° away from the central maximum in the second order by this grating. Light of the wavelength to be measured is deflected by  49° away from the central maximum in the second order. What is the wavelength of this light? (Give answer to the nearest nm)