The formula \cos(A + B) = \cos(A)\cos(B) - \sin(A)\sin(B) is a fundamental identity in trigonometry. It expresses the cosine of the sum of two angles, A and B , in terms of the cosines and sines of those angles. This identity is useful in simplifying expressions and solving problems involving angles. In this equation, \cos and \sin represent the cosine and sine functions, which are key components of the unit circle in trigonometry. This identity helps in various applications, including physics, engineering, and computer graphics, where angle calculations are essential.