Quiz, week 2

What is the range of the function $\sin : \mathbb{R} → \mathbb{R}$? And $\sin : [0, π] → \mathbb{R}$?

What is $d₁((-1, 1), (1, -1))$?

Which of these are sequences?

• $(\sin, \cos)$
• $f(x) = 1/x$ where $f : \mathbb{R}_{++} → \mathbb{R}$
• $f_n = \begin{cases} \sin & \text{if $n$ is even,} \\ \cos & \text{if $n$ is odd} \end{cases}$
• $A_n = [0, n]$ where n is a whole number

How many items are in this set? $\{0, \sin, (2, 3)\}$