lim (x->pi/2) (ln 2x - ln pi)/(sin (5x/2) * cos x) = 1/sin (5pi/4) * lim (x->pi/2) (ln 2x - ln pi)/cos x = | t = x - pi/2 | =
= -2^(1/2) * lim (t->0) (ln (2t + pi) - ln pi)/(-sin t) = 2^(1/2) * lim (t->0) ln (1 + 2t/pi)/sin t = 2^(1/2) * 2/pi = 2 * 2^(1/2)/pi