tgx - 6ctgx + 5 = 0
tgx -6/tgx +6 = 0
tg2x + 5tgx - 6 = 0
Замена tgx = t
t2 + 5t - 6 = 0
D = 25+24 = 49
t1 = (-5+7) / 2= 1
t2 = (-5-7) / 2 = -6
tgx = 1
x = п/4 + пn, n
tgx = -6
x = -arctg 6+ пn
