Given a rectangle 
, draw 
on an extension of 
. Bisect 
and call the midpoint 
. Now draw a semicircle centered
at 
,
and construct the extension of 
which passes through the semicircle
at 
.
Then 
has the same area as 
. This can be shown as follows:
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(1)
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(2)
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(3)
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(4)
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(5)
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