Respuesta :

Answer:

see explanation

Step-by-step explanation:

Not sure quite what you are asking, but

Using the trigonometric identity

cos² x = 1 - sin²x, then

cos²x - sin²x

= 1 - sin²x - sin²x

= 1 - 2sin²x

Thus

cos²30° - sin²30° = 1 - 2sin²30°