proof of Jordan’s Inequality
To prove that
consider a circle (circle with radius = 1 ). Take any point on the circumference of the circle.
Drop the perpendicular from to the horizontal line, being the foot of the perpendicular and the reflection
of at .(refer to figure)
Let
For to be in , the point lies in the first quadrant, as shown.
The length of line segment is .Construct a circle of radius , with as the center.
Length of line segment is .
Length of arc is .
Length of arc is .
Since length of arc (equality holds when )we have .This implies
Since length of arc is length of arc (equality holds true when or ),we have .This implies
Thus we have