Construction 12 Given three segments, construct a segment whose
length is the fourth proportional to the length of the
other three segments.
Given:
three segments, with length a, b, and c
To construct:
a segment with length x,
the fourth proportional
to a, b, and
Steps:
E
Draw a convenient angle ZAOB.
On A copy the segment whose
length is a. Add to that segment
another segment whose length is
equal to b. On OB; copy the segment
whose length is equal to c. Call these
points D, E, and F. Draw DF.
Construct a parallel to DF
through E. This parallel intersects
of at G. The length of
segment FG is the required fourth
proportional
B