The values of cos(a-B) and cosa × cosB + sina × sinB are related through the trigonometric identity:
cos(a - B) = cosa × cosB + sina × sinB
This identity is known as the cosine of a difference formula, and it is used to find the cosine of the difference between two angles.
One thing to notice about this identity is that it involves the product of the cosine of one angle and the cosine of another angle, as well as the product of the sine of one angle and the sine of another angle. This suggests that the values of cos(a-B) and cosa × cosB + sina × sinB are related to each other in a way that involves both the cosine and sine functions.
Another thing to notice is that this identity is a useful tool for simplifying trigonometric expressions that involve the difference of two angles. By using this identity, we can rewrite the expression in terms of the cosine and sine of the individual angles, which can make it easier to work with and evaluate.