cos^2(15°) - sin^2(15°)

Using the trigonometric identity cos^2(x) - sin^2(x) = cos(2x), we have:

cos^2(15°) - sin^2(15°) = cos(2*15°)

cos(30°)

Since cos(30°) is equal to √3/2, the final answer is:

√3/2