State the mathematical names of these shapes. (a) Shape A, (b) Shape B, (c) Shape C. Calculate the area of shape B, the volume of shape C, and the perimeter of shape A. Find the circumference and area of a circle with diameter 8 cm.

The diameter of the circle is $d = 8$ cm.
The radius $r$ is half of the diameter: $r = \frac{d}{2}$.
The formula for circumference $C$ of a circle is $C = \pi d$ or $C = 2\pi r$.
The formula for area $A$ of a circle is $A = \pi r^2$.

Using $C = \pi d$:

Using $\pi \approx 3.14159$:

Using $A = \pi r^2$:

Using $\pi \approx 3.14159$:

The circumference is $\boxed{\text{8\pi cm}}$ or approximately $\boxed{\text{25.13 cm}}$.
The area is $\boxed{\text{16\pi cm}^2}$ or approximately $\boxed{\text{50.27 cm}^2}$.