## anonymous one year ago Can someone help me with this: Find all solutions in the interval [0, 2pi) . 7 tan^3x - 21 tan x = 0

1. DanJS

try factoring tan(x) out first, so tan(x) = 0, recall identities to replace tan^2 and tan by sin and cos maybe

2. DanJS

those probs just play around till you get something in terms of sin and cos using identities and algebra

3. DanJS

$7\tan(x)[\tan^2(x) -3]=0$ $7\tan(x)[\frac{ \sin^2(x) }{ \cos^2(x) } -3]=0$

4. anonymous

Here

5. anonymous

On the very left its pie.k and not pie

6. anonymous

@DanJS what are you doing ? :s

7. anonymous

I mean very right* on the bottom +pie.k

8. DanJS

lol idk, you have it right, use the unit circle, tan(x)=y/x, remember symmetries if needed for multiple answers over the domain

9. anonymous

Thats better

10. DanJS

looks right

11. anonymous

Oh and since its limited between ]0,2pie[ Then you write my answer and add for k=0,1,2