Question

What is the radius of thr brazilian coin that has a circumference of 84.78 mm? Explaim you work. Use 3.14 for pi

Answer 1

we know that

the circumference of a circle is equal to

$C=2\pi r$

where

r is the radius of the circle

in this problem we have

$C=84.78\ mm\\r=?\\\pi=3.14$

Solve for r

$C=2\pi r$

$r=\frac{C}{2\pi}$

substitute the values in the formula

$r=\frac{84.78}{2*3.14}$

$r=13.5\ mm$

therefore

the answer is

the radius of the brazilian coin is $13.5\ mm$

Answer 2

Hello there! Circumference is pi * diameter. Radius is ½ of the diameter. In order to find the diameter, all you have to do is divide the circumference by pi (3.14). 84.78/3.14 is 27. Now, divide that number by 2 to get 13.5. There. The radius of the Brazillian coin is 13.5 mm.