Answer:

Explanation:
One of the trigonometric identities is the identity of addition:

In the case where α = β, we get a new identity, which is commonly known as the double angle identity.

From here, we can also use the identity
.
If we solve for cosine squared, we get:
.
Substituting this value into the identity:

If we solve for sine squared, we get:
.
Substituting this value into the identity:

Therefore, we have three formulas for cos2P:
