Х^2-9х+14
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4x(x-2)=0
4x=0 или х - 2=0
X=0 x=2
используется тождество sin^2 x + cos^2 x = 1
и tg x = sin x / cos x
<span>sina^2a=1-cos^2a=1-9/25=16/25</span>
<span>sina=4/5</span>
<span>sin2a=2sinacosa=2*4/5*3/5=24/25</span>
<span>cos2a=cos^2a-sin^2a=9/25-16/25=-7/25</span>
<span>tg2a=sin2a/cos2a=24/25*(-25/7)=-24/7</span>