Why can the angular size method not be used to determine the physical diameter of a distant exoplanet?

Answer

Distant exoplanets cannot be resolved as disks through a telescope

For distant exoplanets, astronomers cannot resolve them as distinct disks; instead, they appear merely as pinpricks of light, making the angular size measurement based on resolved geometry impossible.

Why can the angular size method not be used to determine the physical diameter of a distant exoplanet?

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