表达式30: left parenthesis, sin left parenthesis, "t" , right parenthesis times left parenthesis, "z" left parenthesis, StartFraction, 5 "t" Over pi , EndFraction , right parenthesis plus 0.7 5 , right parenthesis times StartFraction, "c" Over "h" , EndFraction times sin left parenthesis, "a" , right parenthesis , cos left parenthesis, "t" , right parenthesis times left parenthesis, "z" left parenthesis, StartFraction, 5 "t" Over pi , EndFraction , right parenthesis plus 0.7 5 , right parenthesis times StartFraction, "c" Over "h" , EndFraction plus StartFraction, 125 Over "c" , EndFraction , right parenthesissint·z5tπ+0.75·ch·sina,cost·z5tπ+0.75·ch+125c
定义域t最小值： negative 2 pi−2π
less than or equal to "t" less than or equal to≤t≤
