What is the formula to find the radious of a circle

Question

whpalmer4 · Answer

What do you know about the circle?  Also, the word "radius" does not contain the letter "o" :)

solomonzelman · Answer

the formula for the area of a circle is

$\huge\color{blue}{    A= πr^2 }$

solomonzelman · Answer

and the formula for the circumference is

$\huge\color{blue}{     C=dπ}$   OR   $\huge\color{blue}{     C=2rπ}$ 

b/c  $\color{blue}{     d=2r}$

anonymous · Answer

Thanks I'm trying to make hats for something at church but I couldn't remember how to 😊

whpalmer4 · Answer

Okay, the diameter is the distance all the way across the circle, going through the center.  The radius is the distance from the center to the edge, or exactly 1/2 of the diameter.  

If you know the circumference (think hat size in this case :-) the radius is the circumference divided by $2\pi$ which for your purposes is about 6.3.