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)  $\displaystyle {\csc{{\left({1500}^{\circ}\right)}}}=$  ? + - $\displaystyle {\csc{{(}}}$  $\displaystyle {)}=$ 

(b)  $\displaystyle {\sec{{\left(-{1035}^{\circ}\right)}}}=$  ? - + $\displaystyle {\sec{{(}}}$  $\displaystyle {)}=$ 

(c)  $\displaystyle {\cot{{\left(-{1740}^{\circ}\right)}}}=$  ? - + $\displaystyle {\cot{{(}}}$  $\displaystyle {)}=$