(a) To find the perimeter of the shaded region, we first need to find the angle \\ \angle ADC \\ using trigonometry. We have:

\\ \tan BDC = \frac{4}{3} \\

Thus, \\ BDC = 0.927 \\ radians.

Then, \\ ADC = \pi - 0.927 = 2.214 \\ radians.

The arc length \\ AC \\ is given by:

\\ AC = 5 \times 2.214 = 11.07 \\ cm.

The length \\ AC \\ in the triangle is:

\\ AC = \sqrt{8^2 + 4^2} = 8.94 \\ cm.

Therefore, the perimeter of the shaded region is:

\\ 11.07 + 8.94 = 20.0 \\ cm.

(b) To find the area of the shaded region, we calculate the area of sector \\ ACD \\ and subtract the area of triangle \\ ADC \\ from it.

The area of sector \\ ACD \\ is:

\\ \frac{1}{2} \times 5^2 \times 2.214 = 27.7 \\ cm².

The area of triangle \\ ADC \\ is:

\\ \frac{1}{2} \times 5 \times 4 = 10 \\ cm².

Thus, the area of the shaded region is:

\\ 27.7 - 10 = 17.7 \\ cm².