Whats the rest of the question?
So, the negative would be divided out to make it 3, then square both sides to get rid of the square root and get 9, then subtract 15 and you get -6. <span />
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.
