Dear aspirant hope you are doing well.

Since the TFC curve is horizontal, the difference between the TC and TVC curve is the same at each level of output and equals TFC. This is explained as follows:

The relationship between TC, TVC & TFC

TC – TVC = TFC. The TFC curve is parallel to the horizontal axis while the TVC curve is inverted-S shaped.

Whereas. TC = TOTAL COST

TVC = TOTAL VARIABLE COST

TFC = TOTAL FIXED COST

Hope it's helpful