The solution by @josmiceli was partly incomplete and partly incorrect - so I put my solution below.
tan^2 x = ====> divide both sides by ====>
tan^2(x) = = 0
= 0
This equation deploys in two separate equations:
1) tan(x) = 0, which has two solutions in the given interval: x= 0 and x= ;
and
2) tan(x) = , which also has two solutions in the given interval x= and x= .
Answer. The original equation has 4 solutions in the given interval:
0, , and .