55 БАЛЛОВ!....АЛГЕБРА 10 КЛАСС помогите, НЕ ЗНАЕТЕ, ЛУЧШЕ НЕ ПИШИТЕ ХРЕНЬ ВСЯКУЮ

Question

55 БАЛЛОВ!....АЛГЕБРА 10 КЛАСС помогите, НЕ ЗНАЕТЕ, ЛУЧШЕ НЕ ПИШИТЕ ХРЕНЬ ВСЯКУЮ

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Answer 1

1) т.к. 1.5π<α<2π<br>то cosα>0
⇒cosα = √(1-sin²α) = √(1-9/25) = 4/5

2)sin(π-α)=sinα
sin(π-α)=sinπ*cosα - sinα*cosπ = [т.к. sinπ=0 и cosπ=-1] = sinπ

3) sin(11π/4) = sin(3π/4) = √2/2
cos(13π/4) = cos(π/4) = √2/2
sin(-2.5π) = sin(-0.5π) = sin(-π/2) = -1
cos(-25π/3) = cos(25π/3) = cos(π/3) = 1/2
(√2/2 - √2/2) *(-1) * (1/2) = 0

4) cosα=-2/3
sinα = ±√(1-cos²α) = ±√(1-4/9) = ±√5/3 
⇒|sinα|<1<br>√((1-sinα)/(1+sinα))=√((1-sinα)²/(1-sin²α))=√((1-sinα)²/cos²α)=|(1-sinα)|/|cosα|

√((1+sinα)/(1-sinα))=√((1+sinα)²/(1-sin²α))=√((1+sinα)²/cos²α)=
=|(1+sinα)|/|cosα|

|(1-sinα)|/|cosα| + |(1+sinα)|/|cosα| = (|1-sinα|+|1+sinα|)/|cosα| =
=(1-sinα+1+sinα)/|cosα| = 2/|cosα| = 2/ (2/3) = 3

Comments

СПАСИБО!!!!

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