Ответы: 2
ESENIYA YANCHENKO
2017-09-30 17:10
(1-cos2x/3)/4+(1+cos2x/3)/4=5/8 1-2cos2x/3+cos2x/3+1+2cos2x/3+cos2x/3=5/2 2cos2x/3+2=2,5 2cos2x/4=0,5 cos2x/3=0,25 cos2x/3=-0,5 U cos2x/3=0,5 2x/3=+-5/6+2k U x=+-/6+2k,kz

Evgeniya Kuharenko
2017-10-01 15:59
Task/25178816 * * * t =x/3 , sint +cost=5/8 task/25172737 * * * ———————- sin(x/3) +cos(x/3)=5/8 ; ( sin(x/3) +cos(x/3) ) -2sin(x/3) *cos(x/3) = 5/8 ; 1 — (1/2)sin(2x/3) =5/8 ; sin(2x/3) =3/4 ; * * * cos(2x/3) =1-3/4 =1/4 * * * ( 1 -cos(4x/3) ) /2 = 3/4 ; cos(4x/3) = -1/2 ; * * * cos4t = -1/2 * * * 4x/3 = ±(- /3) +2n , n z ; x = ±/2 +(3/2)*n , n z . ответ : x = ±/2 +(3/2)*n , n z . ——-.— P.S.——-.— sin2= 2sin*cos sin*cos =(1/2)sin2 sin*cos =(1/4)sin2