# Math Help - Inverse Trigonometric Functions

1. ## Inverse Trigonometric Functions

y= arcsin x
Find the right end behavior model, the left hand behavior model, and any horizontal tangents for the function if they exist.

The tangent I can find easily with a calculator, but the behaviors I don't know.

I also need to do it for arccos x, though I think I should be able to get it after knowing arcsin x.

2. Originally Posted by Truthbetold
y= arcsin x
Find the right end behavior model, the left hand behavior model, and any horizontal tangents for the function if they exist.

The tangent I can find easily with a calculator, but the behaviors I don't know.

I also need to do it for arccos x, though I think I should be able to get it after knowing arcsin x.
Hello,

only functions with unchanging monotony (I know that this expression is not appropriate - I mean the first derivative is allways positive or allways negative) have inverse functions. The sin-function has to be bounded to be monotonously increasing (or decreasing). Usually you take the interval $\left [-\frac{\pi}{2}, \frac{\pi}{2}\right ]$.
Thus you have:

$\begin{array}{l}x\mapsto \sin(x), \ \left [-\frac{\pi}{2}, \frac{\pi}{2}\right ] \mapsto [-1, 1] \\ \ \\x\mapsto \arcsin(x), \ [-1, 1] \mapsto \left [-\frac{\pi}{2}, \frac{\pi}{2}\right ] \end{array}$

Therefore examine the arcsin-function if x appraches -1 from the right and when x approaches +1 from the left.

3. So the right is -pi/2 - because the limit as x--> -1 from the right is -pi/2
and the left is pi/2- because the limit as x--> 1 from the left is pi/2.
The answer is pi/2 for both.

What I did I do wrong?