а)1-sin^2A/cos^2A=<u>sin^2A</u>+cos^2A<u>-sin^2</u>A/cos^2A=cos^2A/cos^2A=1
(х-1)(х-2)=(3х+1)(х-2)
x²-2x-x+2=3x²-6x+x-2
2x²-2x-4=0
x²-x-2=0
x²+x-2x-2=0
x(x+1)-2(x+1)=0
(x-2)(x+1)=0
x=2 ∨ x=-1