i already completed a. just stuck in letter b. please explain detail so I can learn as much as possible. thanks in advance

9. (4 points) Simplify each problem as much as possible. Box csc- x sin x Sin 3 (x ) (a) y = cot3 x Sin ( x ) cos 3 (x ) Sing . Sin (x) ~ Sin ? ( x ) COS3 ( x ) Cosa (x ) . Cos (x Sin 3 ( x ) Sin( * ) Sin 3 (x) ( b ) f ( x ) = 4(x + 2) - 2(2 + 1 ) (ac + 2) (x +3)