運算式 2: 5 halves left parenthesis, cos 2 pi "t" , sin 2 pi "t" , right parenthesis plus 5 halves left parenthesis, left bracket, 1 , negative 1 , right bracket , 0 , right parenthesis52cos2πt,sin2πt+521,−1,0
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定義域 t 最小值：
less than or equal to "t" less than or equal to≤t≤
