Circle measuring lesson

When you know one value you can easily find the other.

So when you know the radius, you can find the diameter or when you know the diameter, you can find the radius of any circle.

Try it out:

Radius measures 8, what would the diameter be?

 $r\ =\ 8$ 

  $8\ =\ \frac{1}{2}d$  
1.To find the diameter, do the inverse operation by multiplying both sides by 2
2. You now have :  $\left(2\right)8\ =\ \left(2\right)\ \frac{1}{2}d$  

  $16=\ \frac{2}{2}d$  


  $16\ =\ 1d$  


So; 16 = d

 $d\ =\ 2\left(r\right)$  

 $8\ =\ 2\left(r\right)$  
do the inverse operation to find value of r

 $\frac{8}{2}\ =\ \frac{2}{2}\left(r\right)$  

4 = 1(r)

so: r = 4

d = 2r

r = 1/2d