help

I'll use  x  instead of  theta....it won't matter....

2√tanx=2 sinx tanx     divide  both sides by 2

√tan x  =  sin x tan x      and we can write

sin x tan x  - √tan x  =   0    factor

√tan x  ( sinx - 1)  =  0

So either

√tan x  = 0      square  both sides

tan x  = 0       and  this  happens at  x  =   0 + n*pi

Or

sin x - 1  =  0

sin x  =  1

And  this happens at  x  = pi/2 + n * 2pi

Where  n is an integer