3. Derivatives of the Inverse Trigonometric Functions

by M. Bourne

Recall from when we first met inverse trigonometric functions:

"sin-1x" means "find the angle whose sine equals x".

Example:

If x = sin-10.2588 then by using the calculator, x = 15°. We have found the angle whose sine is 0.2588.


Notation:

We also write: arcsin x to mean the same thing.

It is better to use arcsin x because normally in mathematics, a number raised to the power -1 means the reciprocal. Example: 3-1 = 1/3. Your calculator probably uses the notation: sin-1x. This section mostly uses the sin-1x notation.

You may also wish to go back to background information on inverse trigonmetric equations.


Derivatives of Inverse Trigonometric Functions

The following are the formulas for the derivatives of the inverse trigonometric functions:

math expression

 

Example 1:

Find the derivative of y = cos-15x.

Answer

 

Example 2:

Find the derivative of y = sin-1(1 − x2).

Answer

 

Example 3:

Find math expression if x + y = tan-1( x2 + 3y).


Answer

 

Exercises

1. Find the derivative of y = 3 cos-1(x2 + 0.5).

Answer


2. Find the derivative of y = 4 tan-13x4.

Answer


3. Find the derivative of y = (x2 + 1) sin-14x.

Answer

Let's do this problem in LiveMath. You can change the function reasonably safely.

LIVEMath


4. Find the derivative of sin-1(x + y) + y = x2.

Answer



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