2. Express each complex number in the form $\operatorname{cis} \theta$ where $-\pi< \theta \leq \pi$ :
(a) $\operatorname{cis} 5 \pi$
(b) $\operatorname{cis} \frac{-11 \pi}{6}(\mathrm{c})-\operatorname{cis} \frac{\pi}{4}$

Step 1 ：Express each complex number in the form \(\operatorname{cis} \theta\) where \(-\pi<\theta \leq \pi\):

Step 2 ：(a) \(\operatorname{cis} 5 \pi\)

Step 3 ：(b) \(\operatorname{cis} \frac{-11 \pi}{6}\)

Step 4 ：(c) \(\operatorname{cis} \frac{-\pi}{4}\)

Step 5 ：Find the equivalent angle in the given range for each complex number:

Step 6 ：\(\operatorname{cis} 5 \pi\) has an equivalent angle of \(\operatorname{cis} 3.142\)

Step 7 ：\(\operatorname{cis} \frac{-11 \pi}{6}\) has an equivalent angle of \(\operatorname{cis} 0.524\)

Step 8 ：\(\operatorname{cis} \frac{-\pi}{4}\) has an equivalent angle of \(\operatorname{cis} -0.785\)

Step 9 ：\(\boxed{\text{Final Answer:}}\)

Step 10 ：(a) \(\boxed{\operatorname{cis} 3.142}\)

Step 11 ：(b) \(\boxed{\operatorname{cis} 0.524}\)

Step 12 ：(c) \(\boxed{\operatorname{cis} -0.785}\)