Answer :

Sure, let's solve the problem step by step.

### Step-by-Step Solution

Given:
- Radius of the circle ([tex]\( r \)[/tex]) = 6 cm

#### Part (a): Find the Diameter
The diameter ([tex]\( D \)[/tex]) of a circle can be found using the relationship between the diameter and the radius:
[tex]\[ D = 2 \times r \][/tex]

Calculation:
[tex]\[ D = 2 \times 6 \][/tex]
[tex]\[ D = 12 \][/tex]

So, the diameter of the circle is 12 cm.

#### Part (b): Find the Circumference
The circumference ([tex]\( C \)[/tex]) of a circle can be found using the formula that relates the circumference to the radius:
[tex]\[ C = 2 \times \pi \times r \][/tex]

Calculation:
We need to approximate [tex]\(\pi\)[/tex] as 3.14159 (or use the specific value directly if provided), but the calculation here is already given, so:
[tex]\[ C = 2 \times 3.14159 \times 6 \][/tex]
[tex]\[ C \approx 37.69911184307752 \][/tex]

Therefore, the circumference of the circle is approximately 37.70 cm (rounded to two decimal places).

### Summary
- The diameter of the circle is 12 cm.
- The circumference of the circle is approximately 37.70 cm.