Ребята,тригонометрия,помогите!!!!!

Question

Ребята,тригонометрия,помогите!!!!!

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Answer 1

3. tq300°*sin600°*cos900° =tq(360°-60°)*sin(2*360° -120°)*cos(720°+180°) =
= -tq60°*(-sin120°)*cos180° =√3*sin(180° -60°)* (-1) =√3*sin60°* (-1) = - √3*√3/2  = -1,5.
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4. cos670°/(cos755°*cos775°*cos650°) =
cos(2*360°-50°)/(cos(2*360°+35°)*cos(2*360+55°)*cos(2*360-70°) =
cos50°/(cos35°*cos55°*cos70°) =cos50°/cos70°(cos20°+cos90°)/2 =
2cos50°/cos70°(cos20°+0) = 2sin40°/sin20°*cos20°= 2*2sin20°*cos20°/sin20°*cos20° =4.
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cos35°*cos55° =(cos(35°-55°) +cos(35°+55°) ) /2 =(cos(-20°) +cos90°)/2=
(cos20° +0)/2 =(cos20°)/2 .
cos50° =cos(90° -40°) =sin40° .
cos70° =cos(90° -20°) =sin20° .

Answer 2

3. tg300° = tg(360°-60°)= - tg60°= -√3
                                                           
sin600° = sin(360°+(180°+60°))=sin(180°+60°)= -sin60°= -√3
                                                                                                     2
cos900° = cos(720°+180°)= cos(360° * 2 + 180°)= cos180°= -1

-√3 * (-√3) * (-1) = -3  =  -1.5
            2                 2

Comments

tg60°=√3.