i've figured out part of the problem but i dont' understand what part of it means and i don't know how to do it without a calculator

3 sin^2 x=cos^2 x 0<or equal to x <2pi - what does this inequality mean?

i know that sin^2 x + cos^2 x = 1 so i did this

3 sin^2 x = 1 - sin^2 x

but i don't know what how to solve for x from here and i can't use a calc

thanks!