
A sketch of the locus of a complex number
is shown above, determine the maximum value of
correct to two decimal places where ![]()
Draw tangent lines from the origin to the circle.

Remember tangent lines are perpendicular to the radii

The maximum argument is this angle

I am going to find the angle in two sections

From the diagram the radius of the circle is
and the centre is
. Hence the distance from the origin to the centre is
.

![]()
![]()

![]()
![]()
Hence maximum ![]()