Which expression is equivalent to (cos x + 1)(cos x − 1)?
To find the equivalent expression, we can use the difference of squares formula, which states that (a + b)(a - b) is equal to a^2 - b^2.
In our case, we have (cos x + 1)(cos x - 1). To apply the difference of squares formula, let's consider a = cos x and b = 1.
Using the formula, we can rewrite our expression as cos^2 x - 1^2. Simplifying further, we get cos^2 x - 1.
Therefore, the equivalent expression to (cos x + 1)(cos x − 1) is cos^2 x - 1.