1. <span>(1-4sinx*cosx)*(sin6x-1)=0</span>
<span>(1-4sin(x)cos(x)) (sin(6x)-1)=0</span>
<span>(sin(6x)-1) (-(4sin(x) cos(x)-1))=0</span>
<span>sin(6x) + 4sin(x)cos(x) - 4sin(6x)sin(x)cos(x)-1=0</span>
<span>2sin(2x)+sin(6x) - cos(4x)+cos(8x) -1=0</span>
<span>x≈2.(3.14159n - 1.4399) n ∈ Z</span>
<span>x≈2.(3.14159n - 0.916298) n ∈ Z</span>
<span>x≈2.(3.14159n + 0.1309 ) n ∈ Z</span>
<span>x≈2.(3.14159n + 0.654498 ) n ∈ Z</span>
<span>x≈0.0833333(12.5664n + 3.14159 ) n ∈ Z</span>
30cos2a=30(cos²a - sin²a)=30(cos²a-(1-cos²a))=30(cos²a-1+cos²a)=
=30(2cos²a-1)=30(2*(¹/₅)² -1)=30(2 * ¹/₂₅ - 1)=30(²/₂₅ - ²⁵/₂₅) =
=30 * (- ²³/₂₅) = - ¹³⁸/₅ = - 27.6
Верный ответ под буквой Б
Вот решение:
7²-(6d+4)²=(7-6d-4)(7+6d+4)=(3-6d)(11+6d)