Base Line Discrepancy
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Engineering Aid 2 - Intermediate Structural engineering guide book
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You can compute the length of
BC
by (1) solving
The sum of the angles that make up each of the
overlapping triangles within the quadrilateral is as
follows:
The sum of the closing errors for the four triangles
is (09 + 01 + 07 + 01), or 18 seconds. The average
triangle closure for the four triangles, then, is 18/4, or
04.5 seconds. For third-order triangulation, the
maximum average triangle closure is 05 seconds;
therefore, for the third-order work this closure would
be acceptable.
Base Line Discrepancy
If
AD
is the base line in
figure 15-28,
then
BC
would
be the adjacent baseline.
assume that the baseline
AD
measures 700.00 feet and compute the length of
BC
on the basis of the angles we have adjusted. These angles
now measure as follows:
The natural sine of each of these angles is as
follows:
triangle
ABD
for
AB
and triangle
ABC
for
BC
and (2)
solving triangle
ACD
for
DC
and triangle
DBC
for
BC.
Using the
law of sines
and solving triangle
ABD
for
side
AB,
we have
Solving triangle
ABC
for side
BC,
we have
Solving triangle
ACD
for side
CD,
we have
Solving triangle
DBC
for side
BC,
we have
15-38
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