Simplify a trig expression by multiplying a cosine

The video tutorial explains how to simplify complex fractions by multiplying with the least common denominator (LCD). It then transitions to using trigonometric functions, specifically focusing on expressing terms in sines and cosines. The tutorial highlights the use of Pythagorean identities to further simplify expressions, emphasizing the relationship between sine squared and cosine squared. The instructor provides step-by-step guidance and reinforces key mathematical concepts throughout the lesson.

What identity does the teacher refer to when discussing cosine squared?

What does the teacher conclude about sine squared in relation to cosine squared?