cos(A + B) equals:
AcosA cosB + sinA sinB
BcosA cosB - sinA sinB
CsinA cosB + cosA sinB
DcosA + cosB
Answer & Solution
Correct answer: B. cosA cosB - sinA sinB
cos(A + B) = cosA cosB - sinA sinB. (Note: cos(A - B) = cosA cosB + sinA sinB — sign change.)
Related questions
If cos θ = −1/2 and θ ∈ (π, 3π/2), then θ equals:tan(45° + θ) · tan(45° − θ) is equal to:sin 75° equals:By the law of sines in a triangle, a / sin A is equal to:The general solution of cos x = 0 is:The general solution of sin x = 0 is:If sin θ = 3/5 and θ is acute, then cos θ equals:The angle in radians for 120° is: