angle, A, or the difference in elevation h between
the taped stations.

When the vertical angle is used, the formula
for slope correction is as follows:

When the difference in elevation is used, the
approximate formula derived by Pythagorean
theorem of a right triangle (fig. 12-15) for the
slope correction is as follows:

But for a small slope, d is approximately equal
to s; therefore,

For slopes greater than 5 percent, a closer
approximation of C_{h} can be determined by
expanding the above formula to this form.