<span>1) <em>cos6x cos5x+sin6x sin5x=-1</em>
Формула cosx cos y + sinx sin y = cos (x-y) </span><em>⇒ </em><span><em>cos6x cos 5x + sin6x sin 5x =cos (6x-5x)= cosx=-1</em>
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2)
Формула cosx cos y + sinx sin y = cos (x-y) <em>⇒</em> <em>sin3x cos5x-sin5x cos3x=</em><span><em>sin(5x-3x) =-1 </em></span><em>⇒ sin2x=-1</em>
<span>1)1-2/5=5/5-2/5=3/5- оставшаяся часть .
2)15•5:3=25км
Ответ:25км</span>
(х+12):0,25+16=166
(x+12):0.25= 166-16
(x+12):0.25= 150
x+12= 150×0.25
x+12= 37.5
x= 37.5-12
x= 25.5
У=-sinx+14
y(pi/2)=-sin(pi/2)+14=-1+14=13