Answer:
radius = length of one straight edge of one slice of pizza
minor arc = sum of the lengths of the curved edges of 1, 2, or 3 adjacent slices of pizza
diameter = length of 2 straight edges of 2 opposite slices of pizza
major arc = sum of the lengths of the curved edges of 5, 6 or 7 adjacent slices of pizza
semicircle = sum of 4 adjacent slices of pizza