(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Consider the infinite series s(x)=1-tan^2(x)+tan^4(x)-tan^6(x)+... , where 0<x<pi/4

s'(x)=

A.sin2x

B.cos2x

C.-tan2x

D.-sin2x

E.-cos2x

3. The attempt at a solution

Attempting to derive the series, i get 1-2tanxsec^2x+4tan^3(x)sec^2(x)-6tan^5(x)sec^2(x)+...

am i missing something obvious here? i don't see any trig identities in that that would give any of the answers

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# Homework Help: Derivative of infinite series

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