If m² m'² 2mm' cosx =1,n² n'² 2nn' cosx =1and mn m'n' (mn' m'n) cosx =

If m² m'² 2mm' cosx =1,n² n'² 2nn' cosx =1and mn m'n' (mn' m'n) cosx =0, prove that (1)st m² n²=cosec²x (2)nd m'² n'²=cosecx.