-199,-198,-197,-196,-195,-194,-193,-192,-191
X квадрате=-9х-8
Х квадрате+9х=-8
10х квадрате=-8
(1-sin²a)/cos²a - (cosatga)²=cos²a/cos²a - cos²asin²a/cos²a=
=1-sin²a=cos²a
Otvet: cos²a
(cosa≠0, a≠π/2+kπ,k∈Z)
Tgx/2(cosx+1)=0
tgx/2=0 cosx+1=0
x/2=πn, n∈Z cosx=-1
<u> x=2πn, n∈Z </u> <u>x=π+2πk, k∈Z</u>