Решите неравенство cosx 1/2 - id1550139720230508 от runeto 08.05.2023 18:52

Question

Алгебра: Решите неравенство cosx 1/2

runeto · Accepted Answer

Lim (1-sinx) / (π -2x) неопределенность типа 0/0 .
x→π/2
* * * * * * *
Lim (1-sinx)/(π -2x)=Lim (1-cos(π/2 -x))/(π -2x)=Lim 2sin²(π/4 -x/2)/4(π/4 -x/2) =
x→π/2x→π/2 x→π/2
(1/2)Lim sin(π/4 -x/2)/(π/4 -x/2)* Lim sin(π/4 -x/2) =(1/2)*1*0 =0.
x→π/2x→π/2

* * * 1 -cosα =2sin²α/2 * * *
1 -sinx =1 - cos(π/2 -x) =2sin²((π/2 -x)/2) =2sin²(π/4 -x/2) .
=== ===
Lim (1-sinx)/(π -2x) = Lim (1-cos(π/2 -x)) / 2(π/2 -x) =(1/2)* Lim (1 -cost)/t =
x→π/2x→π/2 t→0
(1/2)* Lim 2sin²(t/2)/ t = (1/2)* Lim sin(t/2)/ (t/2) *Lim sint =(1/2)*1*0 =0.
t →0t→0t→0

|| t =π/2 - x⇒ t→0 ,если x→π/2 ||

Решите неравенство cosx>1/2

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