수식 3: cosine left parenthesis, 2 pi "f" left parenthesis, "x" , right parenthesis "x" , right parenthesiscos2πfxx
3
수식 4: cosine left parenthesis, 2 pi Start integral from 0 to "x" , end integral, "f" left parenthesis, "t" , right parenthesis "d" "t" , right parenthesis negative 4cos2π∫x0ftdt−4