Cos(п-a)=-cosa
cos^2(п-a)=(-cosa)^2=cos^2a
cos(3п/2+a)=sina
cos^2(3п/2+a)=sin^a
сos²a+sin²a=1
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X+y=62
y-x=28
x+y=62
-x+y=28
x+y=62
2y=90
x+y=62
y=45
x+45=62
y=45
x=62-45
y=45
x=17
Ответ:(17;45).
= (49am-21au)+(21mu-49m²) = 7a(7m-3u)-7m(7m-3u) = (7m-3u)(7a-7m)