V =1/3*πR²*H =1/3*π(L/2)²*√3L/2 =1/3*π*3²*3√3 =9√3π.
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2cos2x =1 ;
cos2x =1/2 ;
2x =±π/3 +2π*k ;
x =±π/6 +π*k , k∈Z.
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Loq(0,6) (x-9) > Loq(0,6) 2 ; * * *осн. логарифма 0<0,6<1 лог функц убывающая<br>0< x-9 <2 ;<br> 9--------------------------------
{ √(7-6x -y²) =y +5 ; y =x-1. {√(7-6x -(x-1)²) =x -1 +5 ;y =x-1.
{√(7-6x -(x-1)²) =x +4 ; y =x-1.
{x+4 ≥0 ;7-6x -(x-1)² = (x+4)².
{x ≥ -4 ; x²+6x+5 =0.
{x ≥ -4 ;[x=-5 ;x = -1.
x =-1⇒ y =x-1 = - 2.
ответ: (-1; -2).