Help on math /
struggling on trig identities, its so hard -.-. does anyone know how to solve this? tanx=(sin 4x - sin 2x)/ (cos 4x +cos 2x)?
May 3, 2013
Help on math /
struggling on trig identities, its so hard -.-. does anyone know how to solve this? tanx=(sin 4x - sin 2x)/ (cos 4x +cos 2x)?
4 Comments • Newest first
Wow I don't remember crap...if only you asked me 2 years ago lol
You don't solve it, you prove that the LHS=RHS.
sin2x/cos2x = tan x
tan2x=tanx since sin/cos = tan as an identity, then solve for x. x=0 for both to make the equation true.
x=0
http://oakroadsystems.com/twt/double.htm
http://en.wikipedia.org/wiki/List_of_trigonometric_identities#Angle_sum_and_difference_identities
These questions are often masterd by doing lots of these. It helps if you have clear writing and spacing too so you don't mess up.