1) tg(5pi/24)-tg(7pi/24) 2) (sin(7x)-sin(5x))/(sin(7x)+sin(5x))

1) tg(5π/24) - tg(7π/24) = (sin(5π/24 - 7π/24))/(cos(5π/24)cos(7π/24))
2) (sin(7x) - sin(5x))/(sin(7x)+sin(5x)) = 2cos6xsinx/(2sin6xcosx) = ctg6xtgx