The trigonometric equation is
.
Subtract
from each side.

Factorize the above equation.
\
Apply zero product property.
\
or 
or
.
Solve
.

The general solution of
is
, where
is an integer.
The solution is
, where
is an integer.
Find the solutions on the interval
.
If
,
.
If
,
.
If
,
.
If
,
.
Thus, the solution is
on the interval
.
Solve
.

The solution is
, where
is an integer.
Find the solutions on the interval
.
If
,
.
If
,
.
If
,
.
If
,
.
Thus, the solutions are
and
on the interval
.
\
Therefore, the solutions of
are
,
, and
on the interval
.
The solutions of
are
,
, and
on the interval
.