The trigonometric equation is .

Substitute the value in above equation.

The equation is quadratic equation that can be factored.

Apply zero product property.

or 

or

is invalid.

Since sine domain is .

To solve on a calculator, first set the mode to radians.

Then use the key to obtain.

The solution is not lies in the interval .

So it is invalid solution.

Let we check another angle exists in the interval .

The period of is .

So,

The solution is lies in the interval .

So it is valid solution.

So further all solutions for are not valid for the interval  .

The solution set for is .