Evaluate each of the following: (a) `cos(40^0-theta)-sin(50^0+theta)+(cos^2 40^0+cos^2 50^0)/(sin^2 40^0+sin^2 50^0) ` (b) `(cos70^0)/(sin20^0)+(cos55^0cos e c35^0)/(tan5^0tan25^0tan45^0tan65^0tan85^0) ` (c) `2((cos58^0)/(sin32^0))-sqrt(3)((cos38^0cos e c52^0)/(tan15^0tan60^0t a n75^0))`