For each of the following expressions, use co-terminal angles and the reference angle theorem to write an equivalent expression, and then evaluate exactly. 

(a)  $\displaystyle {\sin{{\left(\frac{{{193}\pi}}{{4}}\right)}}}=$  ? + - $\displaystyle {\sin{{(}}}$  $\displaystyle {)}=$ 

(b)  $\displaystyle {\cos{{\left(\frac{{-{70}\pi}}{{3}}\right)}}}=$? + - $\displaystyle {\cos{{(}}}$ $\displaystyle {)}=$ 

(c)  $\displaystyle {\tan{{\left(\frac{{{175}\pi}}{{6}}\right)}}}=$  ? + - $\displaystyle {\tan{{(}}}$  $\displaystyle {)}=$