Решите уравнение: 1)tg(2x-10 градусов)= 2)2cos(-x)+1=0 3)2cos(-x)+1=0

1)2x-10=π/6+πn
2x=10+π/6+πn
x=5+π/12+πn/2
2)cos(π-x)=-1/2
-cosx=-1/2
cosx=1/2
x=+-π/3+2ππn
3)cos(π/3-x)=-1/2
π/3-x=+-2π/3+2πn
-x=-π/3+2π/3+2πn⇒-x=π/3+2πn⇒x=-π/3+2πn
-x=-π/3-2π/3+2πn=⇒-x=-π+2πn⇒x=π+2πn