cos26*cos14=1/2[cos40+cos12]
cos2x*cosx=1/2[cos3x+cosx]
cos2.5xcos0.5x=1/2[cos3x+cos2x]
cos3x+cosx=cos3x+cos2x
cosx=cos2x=2cos^x-1
cosx=t
2t^-t-1=0
t=(1+-3)/4
t1=1
t2=-1/2
cosx=1 x=2Пn
cosx=-1/2
x=2П/3+2Пn
x=4П/3+2Пn
<em>х(х-30)=675;</em>
<em>х²-30х-675=0;</em>
<em>х₁=-15;</em>
Вот это решение..........
→ → → → → → → → → → → → → → →
AB+CD-MN+DC+BN-KM = AB + BN +NM +MK +<u>CD +DC</u> = AK + 0 = AK
1целая 11/24+13/36=1целая33/72+26/72=1 целая59/72