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

cosx=12/13

3pi/2 is less than or equal to x is less than or equal to 2pi

2. Relevant equations

sin2x = 2sinxcosx

cos2x = 1-2(sinx)^2

tan2x = (2tanx)/(1-(tanx)^2)

3. The attempt at a solution

Using the tan2x formula, I get -60/47. Using the sin2x (sin2x=-120/169) and cos2x (cos2x=119/169) formulas, than dividing sin2x by cos2x, I get -120/119.

tan2x=2(-5/12)/(1-2(-5/12)^2)

=(-10/12)/47/72

=-60/47

Why am I getting different values?

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# Homework Help: Calculate tan2x

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