How to simplify a trigonometric expression by squaring a binomial

The video tutorial explains how to expand and simplify the expression (sin X + cos X)^2 using the FOIL method. It demonstrates combining like terms and applying trigonometric identities to simplify the expression further. The tutorial concludes with the final simplified form of the expression, emphasizing the importance of understanding trigonometric identities in simplification.

Explain the process of combining like terms in the expression derived from sine and cosine.

What does the square of sine X plus cosine X represent in trigonometric terms?