What is the circumference of the circle? r=1.8 (C = πd

Circumference, as you noted, is represented as C = πd where d is the diameter of the circle.

The diameter is d = 2r, where r is the radius:

d = 2 (1.8)

d = 3.6

You can represent the circumference in terms of π. In this case, the circumference would be 3.6π.

You can also find the exact value by substituting π for 3.14:

3.6 (3.14) = 11.304

The circumference can be either 3.6π or 11.304.

C = πd

As you know d = 2r = 2 (1.8) = 3.6

So C = πd = 3.14 x 3.6 = 11.304 units

Answer

C = 11.304 units