Respuesta :
Please be careful in the future regarding the options. These options look like cos of 2x, rather than cos(squared) of x.
The answer is B) -cos²(x)
(sin(x) + a) (sin(x) - a) = -cos²(x)
The answer is B) -cos²(x)
(sin(x) + a) (sin(x) - a) = -cos²(x)