Tell whether the statement is true or false.
-$$\cos - 23 ^ { \circ } = \cos 40 ^ { \circ } \cos 63 ^ { \circ } + \sin 40 ^ { \circ } \sin 63 ^ { \circ }$$

Question

Quizplus · Accepted Answer

This statement is true because it is an application of the cosine of a difference identity, $\cos (A - B) = \cos A \cos B + \sin A \sin B$, with $A = 40^\circ$ and $B = 63^\circ$, thus $A - B = -23^\circ$.

Tell Whether the Statement Is True or False cos⁡−23∘=cos⁡40∘cos⁡63∘+sin⁡40∘sin⁡63∘\cos - 23 ^ { \circ } = \cos 40 ^ { \circ } \cos 63 ^ { \circ } + \sin 40 ^ { \circ } \sin 63 ^ { \circ }cos−23∘=cos40∘cos63∘+sin40∘sin63∘

Tell Whether the Statement Is True or False $\cos - 23 ^ { \circ } = \cos 40 ^ { \circ } \cos 63 ^ { \circ } + \sin 40 ^ { \circ } \sin 63 ^ { \circ }$