Discrete Math - Sets question

Question

$C = \{1,2\}$

$D = \{1,2,6,7\}$

Considering the sets above are the following statements correct?

$C \cup D = \{1,2,6,7\}$

$C \cap D$ = {$1,2$}

$(C \times D) \cap (D \times C) = \{\{1,1\}, \{1,2\}\}$

Answer 1

Your $C\cup D$ and$\quad C\cap D$ are correct.

Now $C$x$D$ $=$ {1,1},{1,2},{1,6},{1,7},{2,1},{2,2},{2,6},{2,7}

and $D$x$C=$ {1,1},{1,2},{2,1},{2,2},{6,1},{6,2},{7,1},{7,2}

($C$ x $D$) $\cap$ ($ D$ x $C$)={1,1},{1,2},{2,1},{2,2}