РЕШИТЕ, ПОЖАЛУЙСТА ,В1,В3, С1-С2. ЗАДАНИЕ ВО ВЛОЖЕНИИ, 1 ВАРИАНТ

Question

РЕШИТЕ, ПОЖАЛУЙСТА ,В1,В3, С1-С2. ЗАДАНИЕ ВО ВЛОЖЕНИИ, 1 ВАРИАНТ

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Answer 1

B1
(sin55sin9-cos55sin(90-9))/(cos32-cos58)(cos32+cos58)=
=(sin55sin9-cos55cos9)/2sin13sin45*2cos13cos45=
=-cos64/(√2/2*√2/2*sin26)=-2cos64/sin(90-64)=-2cos64/cos64=-2
B3
1/2*sinx√(16-x²)=0
ОДЗ  (4-х)(4+х)≥0⇒x∈[-4;4]
16-x²=0⇒x=-4 U x=4
sinx=0⇒x=πn+ОДЗ⇒x={-π;0;π}
C1
(1-cosπ/6)²/4+(1-cos7π/6)²/4+(1-cos5π/6)/4+(1-cos11π/6)/4=
cos7π/6=-cosπ/6    cos5π/6=-cosπ/6    cos11π/6=cosπ/6
=(1-cosπ/6)²/4+(1+cosπ/6)²/4+(1+cosπ/6)/4+(1-cosπ/6)/4=
=1/2(1-2cosπ/6+cos²π/6+1+2cosπ/6+cos²π/6)=1/2(2+2cos²π/6)=
=1+cos²π/6=1+1/4=1,25
C2
2cos²y-1+4acosy+2a²+1=0
2cos²y+4acosy+2a²=0
2(cos²y+2acosy+a²(=0
2(cosy+a)=0
cosy+a=0
cosy=-a
-a<-1⇒a>1 U -a>1⇒a<-1<br>a∈(-∞;-1) U (1;∞)