For Eclipsing Binaries, why is the mass calculation generally more direct and accurate?

Answer

The orbital plane is viewed nearly edge-on, minimizing inclination uncertainty

When $i$ is approximately $90^ ext{circ}$, the measured separation is very close to the true semi-major axis ($a \sin i \approx a$), thus minimizing the uncertainty introduced by unknown inclination.

For Eclipsing Binaries, why is the mass calculation generally more direct and accurate?
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