original_query: What is the purpose of the axis of symmetry in a paraboloidal reflector?
query: What is the purpose of the axis of symmetry in a paraboloidal reflector used in solar cooking?
answer: In a paraboloidal reflector used for solar cooking, the axis of symmetry is aimed at the sun.  This ensures that parallel rays of sunlight are concentrated to a single point (the focus) where the cooking pot is placed, maximizing heat absorption.