Question

The circumference of a coin is 7.42cm. What is the diamater,radius, and area? use 3.14 for π

Answer 1

So circumference of a circle is$C=2*3.14*r$ , with r = radius. Using what we have, we can solve for r.

$7.42=2*3.14*r$

Firstly, multiply everything on the right side of the equation. $7.42=6.28r$

Next, just divide both sides by 6.28, and your answer should be $1.18=r$

Next, the diameter is just the radius times 2, which is 2.36.

Lastly, Area of a circle is $A=3.14*r^2$ . Using what we have, we can solve for area.

$A=3.14*1.18^2$

Firstly, solve the exponents: $A=3.14*1.3924$

Next, just multiply the right side, and your answer should be $A=4.37$

In short, 1.18 cm is the radius, 2.36 cm is the diameter, and the area is 4.37 cm^2