1waise..
given thing = cos(x/2)cos(x/4)cos(x/8).....cos(x/2^n)
= sin[2n+1(x/2n)]/2n+1 sin(x/2n)
abhi toh ho jaega yahan se...
put n-> infinity.
Simplify
\prod_{n=1}^{\infty }{cos(\frac{x}{2^n})}
it comes out to be \frac{sinx}{x} but how?
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7 Answers
11well there's a formula:
cosAcos2Acos4A.......cos2n-1A = sin2nA/ 2nsinA
1yeah i've seen that before,but couldn't remember,ok thanks i'll try that