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Subsection 2.12.2 Exercises

Exercises — Stage 1

1

Give the domains of each of the following functions.

\begin{align*} \mbox{(a) } f(x)\amp=\arcsin(\cos x) \amp \mbox{(b) } g(x)\amp=\arccsc(\cos x)\\ \mbox{(c) } h(x)\amp=\sin(\arccos x) \end{align*}
2

A particle starts moving at time \(t=10\text{,}\) and it bobs up and down, so that its height at time \(t \geq 10\) is given by \(\cos t\text{.}\) True or false: the particle has height 1 at time \(t=\arccos(1)\text{.}\)

3

The curve \(y=f(x)\) is shown below, for some function \(f\text{.}\) Restrict \(f\) to the largest possible interval containing \(0\) over which it is one--to--one, and sketch the curve \(y=f^{-1}(x)\text{.}\)

4

Let \(a\) be some constant. Where does the curve \(y=ax+\cos x\) have a horizontal tangent line?

5

Define a function \(f(x)=\arcsin x + \arccsc x\text{.}\) What is the domain of \(f(x)\text{?}\) Where is \(f(x)\) differentiable?

Exercises — Stage 2

6

Differentiate \(f(x)=\arcsin\left(\dfrac{x}{3}\right)\text{.}\) What is the domain of \(f(x)\text{?}\)

7

Differentiate \(f(t)=\dfrac{\arccos t}{t^2-1}\text{.}\) What is the domain of \(f(t)\text{?}\)

8

Differentiate \(f(x)=\arcsec(-x^2-2)\text{.}\) What is the domain of \(f(x)\text{?}\)

9

Differentiate \(f(x)=\dfrac{1}{a}\arctan\left(\dfrac{x}{a}\right)\text{,}\) where \(a\) is a nonzero constant. What is the domain of \(f(x)\text{?}\)

10

Differentiate \(f(x)=x\arcsin x + \sqrt{1-x^2}\text{.}\) What is the domain of \(f(x)\text{?}\)

11

For which values of \(x\) is the tangent line to \(y=\arctan (x^2)\) horizontal?

12

Evaluate \(\ds\diff{}{x}\{\arcsin x + \arccos x\}\text{.}\)

13 (✳)

Find the derivative of \(y=\arcsin \!\big(\frac{1}{x}\big)\text{.}\)

14 (✳)

Find the derivative of \(y=\arctan \big(\frac{1}{x}\big)\text{.}\)

15 (✳)

Calculate and simplify the derivative of \((1+x^2)\arctan x\text{.}\)

16

Show that \(\ds\diff{}{x}\left\{\sin\left(\arctan(x) \right)\right\} = (x^2+1)^{-3/2}\text{.}\)

17

Show that \(\ds\diff{}{x}\left\{\cot\left(\arcsin(x) \right)\right\} = \dfrac{-1}{x^2\sqrt{1-x^2}}\text{.}\)

18 (✳)

Determine all points on the curve \(y=\arcsin x\) where the tangent line is parallel to the line \(y=2x+9\text{.}\)

19

For which values of \(x\) does the function \(f(x)=\arctan(\csc x)\) have a horizontal tangent line?

Exercises — Stage 3

20 (✳)

Let \(f(x) = x + \cos x\text{,}\) and let \(g(y) = f^{-1}(y)\) be the inverse function. Determine \(g'(y)\text{.}\)

21 (✳)

\(f(x) = 2x-\sin(x)\) is one--to--one. Find \(\big(f^{-1}\big)'(\pi-1)\text{.}\)

22 (✳)

\(f(x) = e^x+x\) is one--to--one. Find \(\big(f^{-1}\big)'(e+1)\text{.}\)

23

Differentiate \(f(x)=[\sin x +2]^{\arcsec x}\text{.}\) What is the domain of this function?

24

Suppose you can't remember whether the derivative of arcsine is \(\dfrac{1}{\sqrt{1-x^2}}\) or \(\dfrac{1}{\sqrt{x^2-1}}\text{.}\) Describe how the domain of arcsine suggests that one of these is wrong.

25

Evaluate \(\displaystyle \lim_{x\to 1}\left( (x-1)^{-1}\left(\arctan x - \frac{\pi}{4}\right)\right).\)

26

Suppose \(f(2x+1)=\dfrac{5x-9}{3x+7}\text{.}\) Evaluate \(f^{-1}(7)\text{.}\)

27

Suppose \(f^{-1}(4x-1)=\dfrac{2x+3}{x+1}\text{.}\) Evaluate \(f(0)\text{.}\)

28

Suppose a curve is defined implicitly by

\begin{equation*} \arcsin(x+2y)=x^2+y^2 \end{equation*}

Solve for \(y'\) in terms of \(x\) and \(y\text{.}\)