## Thomas' Calculus 13th Edition

a. Domain : The set of all $(x,y)$ corresponding to $-1 \leq (y-x) \leq 1$ . b. Range: The range is $\dfrac{-\pi}{2} \leq z\leq \dfrac{\pi}{2}$ c. The level Curves are the straight lines whose form as $y-x=c$ and $-1 \leq c \leq 1$. d. Boundary points is at the two straight lines such as $y=1+x$ and $y=-1+x \implies y=x-1$ e. Closed f. Unbounded