#### Answer

9$ \pi$ cm

#### Work Step by Step

CD is the minor arc of the circle
We need to find out the length of CD
In a circle whose circumference is c, the length l of an arc whose degree measure is m is given by l =$\frac{m}{360}$ * c
Therefore for given circle c = 2$\pi$ r = 2$\pi$ * 12 = 24$\pi$ cm
given m =135$^{\circ}$
Therefore lCD = $\frac{m}{360}$ * c
= $\frac{135}{360}$ * 24$\pi$
=9$ \pi$ cm