If cos a/cos b + sin a/sin b = cos c/cos b + sin c/sin b=1, where a and c do not differ by an even multiple of π, find: cos a.cos c/cos^2 b + sin a.sin c/sin^2 b ?
If cos a/cos b + sin a/sin b = cos c/cos b + sin c/sin b=1, where a and c do not differ by an even multiple of π, find: cos a.cos c/cos^2 b + sin a.sin c/sin^2 b ?