maths
posted by piyush yadav on .
If S=1/2^2cos1 + 1/cos1¤cos2+1/2^3 cos1 ¤cos2¤cos2^2 + .......... upto 10 terms . If S= sina(cotbcotc) where a,b,c€N Then find value of a+b+c. where¤ means multipication sign

use brackets or the * symbol to show multiplication.
Secondly lack of brackets to show the order of operation makes an attempt at a solution futile. 
pls. do ques . its really a good problem