<span>1)sinx+sin2x+sin3x+sin4x = (sinx+sin3x)+(sin2x+sin4x) =2sin2x× cosx+2sin3x× cosx =2cosx(sin2x+sin3x) =4sin(5x/2)× cos(x/2)× cosx</span>
Зашифрована 4. 4+12=16=4+4+4+4
<span>99 целых 1/9 : 44,6=20/9
</span><span>4 целых 7/12 * 4/11=5/3
20/9-5/3=5/9
5/9+13 11/18=85/6
85/6:25,5=5/9
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