The person is standing 16m from the circular monument park. Her lines of sight form tangent to the monument with an angle of
. Let the arc formed by her sight be the minor arc and the remaining arc of the circular monument be major arc.
Let the measure of minor arc be
.
Therefore, the major arc is

Now, Applying Tangent-Tangent Angle theorem which states that If an angle is formed by two intersecting tangents, then the measure of the angle is one half the difference of the measures of the intercepted arcs (the major arc minus the minor arc).
So,






