Derivative of Inverse Secant

Learn how to derive the derivative of inverse secant

[davidsorensen]

You can't introduce the hypotenuse and adjacent and opposite sides before you draw the triangle without confusion. Plot the inverse secant function, then consider the two cases, y is either in quadrant I or quadrant II, so the angle y should be in those quadrants. When you label the hypotenuse in the second quadrant, you have to label it -x so you are referring a positive length.