# Thread: pi/9 is a root

1. ## pi/9 is a root

How do I show that $\pi$/9 is a root of 33*tan(x)^4-27*tan(x)^2-tan(x)^6+3?

2. Substitute into the formula and go from there.

3. Thank you, Catherine. Yes putting t=Pi/9 in

tan(3t) = (3tan(t)-tan(t)^3) / (1-3tan(t)^2)

looks like it will do it.

(for some reason your identity has
disappeared, but in case someone reads this I put it