The sine function is 1 at 90 degrees or
I find it hard to type the problem on the computer, so I included a picture with a note on where I am stuck. I know I can't divide "1" by "sin2theta" to get 30 degrees, so I don't know what to do next. Thanks.
If you substitute these back into the original equation, you'll see that the solution is and the second angle of is an extraneous solution introduced when you squared both sides.