For problems 12-15, use your knowledge of u-substitution and the Fundamental Theorem of Calculus to evaluate each denite integral. Leave answers in radical form, in terms of In, or in terms of 3, etc. 14. f 0" cos2 (x) sin(x) dx cos (:0) sin (9:) 15 . If c0t(x) dx (hint: rewrite cot(x) as 6