The range of a projectile is
.
Where is the initial velocity in feet per second.
is the angle of elevation.
Initial velocity is .
Substitute in
.
Differentiate with respect to .
The change in angle is .
Convert the angle degrees measure into radians measure.
\.
Consider .
Convert the angle degrees measure into radians measure.
\.
.
Substitute and
in the above equation.
Consider .
Substitute in the above equation.
Find the change in range.
\The approximate change in range is .