Final answer:
The question appears to contain a typo and seems to be asking about the identity of cos^4(theta). There is no direct identity for cos^4(theta), but it can be derived using power-reducing or double angle identities.
Step-by-step explanation:
I believe there is a typo in your question. You seem to be asking about the identity of cos4θ. In trigonometry, there isn't an identity that directly gives cos4θ but it can be expressed in terms of other functions using power-reducing or double angle identities. For instance, cos2θ can be written as ((1 + cos(2θ)) / 2) and then you could square this expression to find cos4θ. Let me know if you seek a specific identity or expression.