Answer:
The diameter of the circle is 9.7mm
Step-by-step explanation:
The area of a circle is given by the following formula:
[tex]A_{c} = \pi r^{2}[/tex]
In which r is the radius.
In this problem, we have that
[tex]A_{c} = 74 mm^{2}[/tex]
So
[tex]74 = \pi r^{2}[/tex]
[tex]r = \sqrt{\frac{74}{\pi}}[/tex]
[tex]r = 4.85mm[/tex]
The diameter is twice the radius:
So
[tex]d = 2r = 2*4.85 = 9.7[/tex]
The diameter of the circle is 9.7mm