(2x-y-3)²+(x-3y-1)²=(2x-y)²-6(2x-y)+9+
(x-3y)²-2(x-3y)+1=4x²-4xy+y²-12x+6y+9+
x²-6xy+9y²-2x+6y+1=5x²+10y²-10xy-14x+12y+10
5 в 2 степени.......... ..
4.sinπ/6+3tg²π/4+cotgπ/4+2.cosπ/3=4.0,5+3.1²+1+2+0,5=
=2+3+1+0,5=6,5
(sinπ/6=cosπ/3)=0,5 , tgπ/4=cotgπ/4=1)
Cos x = sin 2x
cos x - 2sinx cosx =0
cosx ( 1-2sinx) = 0
cos x= 0
x=π/2 + πn,n ∈ Z
sinx = 1/2
x=(-1)^k × π/6 + πk,k ∈ Z