упростить (1-2cos^2 10a)tg5a
(1-2cos^2 10a)tg5a=(2sin^2 10a-1)tg5a=(2(2sin5a*cos5a)^2-1)sin5a/cos5a=(8sin^2 5a*cos^2 5a-1)sin5a/cos5a=8sin^3 5a*cos 5a- tg5a