Сtg9π/5>0 3ч
sin5π/9>0-2ч
ctg9π/5sin5π/9>0
3sin²x-4sinxcosx+cos²x=0/cos²x
3tg²x-4tgx+1=0
tgx=a
3a²-4a+1=0
D=16-12=4
a1=(4-2)/6=1/3⇒tgx=1/3+πn,n∈z
x1=2π+arctg1/3∈(3π/2;4π)
x2=3π+arctg1/3∈(3π/2;4π)
a2=(4+2)/6=1⇒tgx=1⇒x=π/4+πk,k∈z
х3=9π/4
x4=13π/4∈(3π/2;4π)
(2+1/3;-1/3) или (2,3;-0.3) как больше нравится
<span>Решение
</span>√2sinx*cosx=cosx
<span>√2sinx*cosx - cosx = 0
cosx*(</span>√2sinx - 1) = 0
1) cosx = 0
x₁ = π/2 + πk, k ∈ Z
2) √2sinx - 1 = 0
sinx = 1/√2
x = (-1)^n * arcsin(1/√2) + πn, n ∈ Z
x₂ = (-1)^n * (π/4)<span> + πn, n ∈ Z
</span>Ответ: x₁ = π/2 + πk, k ∈ Z ; x₂ = (-1)^n * (π/4)<span> + πn, n ∈ Z</span>
А-3
Б-1
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