The United States Treasury Department set the dimensions of a one-dollar coin in 1979. A one-dollar coin has diameter that measures 26.5 millimeter. What is the circumference of the coin to the nearest hundredth of a millimeter? Please help me <3 : :

What is the sum of the geometric series in which a1 = 7, r = 3, and an = 1,701? hint: cap s sub n equals start fraction a sub one left parenthesis one minus r to the power of n end power right parenthesis over one minus r end fraction comma r ≠ 1, where a1 is the first term and r is the common ratio