Answer:

Step-by-step explanation:
We are given the equation: 

First, we can divide everything by 2: 

Notice that we have an equation in quadratic form. Namely, if we make a substitution where u = sin(x), we acquire: 

Solve for u. Factor: 

Zero Product Property: 

Solving for both cases: 

And by substitution: 

For the first case, recall that sin(x) is -1/2 for every 7π/6 and every 11π/6. Hence, for the first case, our solutions are: 

Where n is an integer. 
For the second case, sin(x) is -1 for every 3π/2. Thus: 

All together, our solutions are: 
