Question 137510
What are the surfaces on the coin?
You have the front, the back and the rim. The front and back are the same -- just the area of a circle.

The rim (side) can be found using formulas for surface area of cylinders. OR, in this case, you can mentally "unroll" the side. Imagine making a vertical cut and then unrolling. What do you end up with? 

Right, you end up a rectangle with sides of 1.45mm and the circumference of the circle making up the front/back.

Net, you have three areas

{{{Surface area = AreaFront + AreaBack + AreaSide}}}
{{{A = 2*AreaFront + AreaSide}}}

The area of a circle is given by {{{A=pi*r^2}}} . we are given the diameter, so we need to divide by 2 to get the radius.

The area of a rectangle is given by {{{A = Length*Width}}}. We are given the width and need to calculate the length. The length is just the circumference. Circumference is given by {{{C=pi*d}}}.

Now you have everything you need.

{{{A = 2*(pi*(23.05/2)^2)  + (pi*23.05 * 1.45)}}}

You can it in from here