\
The distance from the Sun to Earth is approximately
.
The distance from the Sun to Mercury is approximately
.
The elongation angle is the angle formed between the line of sight from Earth to the Sun and the line of sight from Earth to Mercury
.
Consider the distance between the earth and mercury as
.
Draw a diagram for the situation:
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Observe the figure:
\
.
Apply the Law of Sines for triangle
:




and
.
.
.
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Apply the Law of Sines for triangle
for
:

\
Apply the Law of Sines for triangle
for
.

Thus, Possible distances between Earth and Mercury are approximately
or
.
\
Possible distances between Earth and Mercury are approximately
or
.