Light with wavelength 530 nm falls on a transparent diffraction grating with period 1.50m, find the angle,

Light with wavelength 530 nm falls on a transparent diffraction grating with period 1.50μm, find the angle, relative to the grating normal, at which the Fraunhofer maximum of highest order is observed provided the light falls on the grating
(a) At right angles;
(b) At the angle 60° to the normal.