Answer:
The given equation is
Where , this interval means that we need to find the solution of the equation in every quadrant, remember that trigonometric equations are periodical, that means its solution repeats in other quadrants.
First, we need to make a variable change where and , so the equation is
Now, we can solve the equation as a quadratic equation.
We know this equation has two solutions
To find these solutions, we use the quadratic formula
Where
Replacing these values, we have
So,
But, , so