Let us solve problem on derivative of inverse tangent
-->Derivative of inverse tangent angle when z =sixty.
Angle = arctan z
Angle = arctan sixty
Angle = 1.554131203081 radian
In degree mode 89.045158746128
Derivative of inverse tangent angle when z=90.
Angle = arctan z
Angle = arctan ninety
Angle = 1.5596856728973 radian
In degree mode = 89.363406424037.
