The relationship between TVC and AVC is shown in Figure 5.5. The slope of a ray
to the TVC curve at any point represents the value of AVC. For example, at point x,
AVC = TVC*/Q2. The ray is tangential to the curve of this point and AVC is therefore
at a minimum at output Q2. A ray drawn to any other point of the TVC curve has a
greater slope. AVC falls as we approach Q2 and rises as we move away from Q2. This is
illustrated in the shape of AVC in Figure 5.5b.