Find the condition of a,b for which the function f(x)(0≤x≤2π) satisfying the following equality can be determined uniquely,then determine f(x), assuming that f(x) is a continuous function at 0≤x≤2π.
f(x)=2πa∫02πsin(x+y)f(y)dy+2πb∫02πcos(x−y)f(y)dy+sinx+cosx