$\"\"$

The trigonometric equation is $\"\"$ .

$\"\"$ (Write original equation)

$\"\"$ (Apply sum - to - product formula: $\"\"$ )

$\"\"$ (Simplify)

$\"\"$ (Apply odd identity: $\"\"$ ) $\"\"$

The factor $\"\"$ equal to zero, you can find that the solutions in the interval $\"\"$ are $\"\"$ .

The factor $\"\"$ yields no additional solutions, so you can conclude that the solutions are of the form is $\"\"$ , where n is integer. $\"\"$

The solution is $\"\"$ .