 Consider the average temperatures,

at which heat is input and output, respectively.Replace "TH" and "TC" in Equation () by 〈"TH"〉 and 〈"TC"〉 respectively.For the Carnot cycle, or its equivalent, the average value 〈"TH"〉 will equal the highest temperature available, namely "TH", and 〈"TC"〉 the lowest, namely "TC".