Which identity gives cos(A − B) for any two angles A and B?
- sinA cosB + cosA sinB
- cosA cosB − sinA sinB
- cosA cosB + sinA sinB
- sinA cosB − cosA sinB
Show answer and solution
Correct answer: C. cosA cosB + sinA sinB
Using the distance between two points on the unit circle, cos(A − B) works out to cosA cosB + sinA sinB.