An x-ray beam of wavelength A undergoes first-order reflection from a crystal when its angle of incidence to a crystal face ts 23o, and an x-ray beam of wavelength 97 pm undergoes third-order reflection when its angle of incidence to that face is 60o. Assuming that the two beams reflect from the same family of reflecting planes, find

(a) The inter planar spacing and

(b) The wavelength A.