A reversible engine operates between temperature $$T_1$$ and $$T_2$$. The energy rejected by this engine acts as an input for another reversible engine at temperature $$T_2$$, which rejects to a reservoir at temperature $$T_3$$. What is the relation between $$T_1, T_2$$ and $$T_3$$?

A

$$T_2 = \frac{T_1 + T_3}{2}$$

B

$$T_2 = \sqrt{T_1^2 + T_3^2}$$

C

$$T_2 = \sqrt{T_1T_3}$$

D

$$T_2 = \frac{T_1 - T_3}{2}$$