The equation cannot be verified. It is not true for all values of x.
An initial approach is to see if it is a trigonometric identity.
Starting with the left side and converting to sines and cosines,
The left side cannot equal the right side for all values of x since
To prove it is not an identity, it is sufficient to find one value for x which does not satisfy both sides. For example, working in degrees, if x = 30 degrees,
Since the left side does not equal the right side for the value x = 30 degrees, the equation is not an identity and cannot be verified.