Question 17070
First of all you need to find the formulas for the circumference {{{(C/d)=pi}}} and the area of a circle is {{{r^2*pi}}}
C=circumfence
d=diameter 17.2=(8.6*2)
r=radius (8.6)
pi=3.14

So plug in your numbers first the area

{{{8.6^2*pi}}}=232.3521927

now the circumfrence

{{{(C/17.2)=3.14}}}
multiply 17.2 on both sides of the = sign
{{{17.2*(C/17.2)=(3.14*17.2)
C=54.03539364