Cosx (tgx-3/tgx+5,5) = 0

1 / cosx=0 x = π/2+πk k∈Z не подходит

2 / tgx-3/tgx+5.5=0

tgx⇔sinx≠0 cosx≠0 ⇒x≠ (π/2) * k k∈Z

tgx=t t-3/t+5.5=0 ⇒t²+5.5t-3=0

√D=√ (5.5²+4*3) = 11√3

t1=1/2 (-5.5+√3) t2=1/2 (-5.5-√3)

x1=arctg (-2.75+√3/2) + πk x2=arctg (-2.75-√3/2) + πk k∈Z