Solve 3tan^2 x-1=0 for all solutions [0, 2pi]?

1 Answer
Oct 17, 2016

x in {pi/6, (5pi)/6, (7pi)/6, (11pi)/6}

Explanation:

3tan^2(x) - 1 = 0

=> tan^2(x) = 1/3

=> tan(x) = +-1/sqrt(3)

If we check the unit circle, we find that |tan(x)| = 1/sqrt(3) when |sin(x)| = 1/2 and |cos(x)| = sqrt(3)/2, that is, at x = pi/6+npi or x=-pi/6+npi.

Finding what values for n put these within the interval [0, 2pi), we get n in {0, 1} for x=pi/6+npi and n in {1, 2} for x = -pi/6+npi. Thus, our total solution set is

x in {pi/6, (5pi)/6, (7pi)/6, (11pi)/6}