Найти производную функции y=tg^2(x/2) . .

1)y=tg^2(x/2)
2 tg(x/2)d/dx [tg(x/2)]
2 tg(x/2)(sec^2 (u2) d/dx [x/2])
2 tg(x/2)sec^2(x/2) d/dx [x/2]
2 tg(x/2)sec^2(x/2)(1/2 d/dx [x/1])
tg(x/2)sec^2(x/2) d/dx [x]
tg(x/2)sec^2(x/2)*1
tg(x/2)sec^2(x/2)
sec^2(x/2)tg(x/2)