Sorry, I meant to write "square root of two". The problem is in AB College Calculus in "Limits using Trig Identites". I will re-write the question below;

I was wondering why, 1−2sin^2(θ) can be factored using the difference of squares to equal,(1+(square root of two) ​sin(θ))​(1−(square root of two)sin(θ)?  If I foil, how does (Square root of two sin)(square root of two sin) =2sin^2, when (2)(2^2) cannot be factored to (square root of two)(square root of two), that would equal two.

Hi T R,

I'm not quite sure what you're meaning by "(2)(2^2)" or where that is coming from. Can you explain how you got this?

Here's how the expression you gave can be expanded: