2cos(2x-П/4)=1/2,
cos(2x-П/4)=1/4,
2x - П/4 = arccos(1/4) +,-2П*n,
2x = П/4 + arccos(1/4) +,-2П*n,
x = П/8 + 0,5*arccos(1/4) +,-П*n,
n = 0,1,2,3,...
2П*n - период.
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ОТВЕТ:
x = 0,5*arccos(1/4) + П( 1/8 +,-n) ,
n = 0,1,2,3,...
2П*n - период.