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
Simplifying an equation, a student reaches a statement that can never be true. The equatioAfter squaring both sides of a radical equation, a student finds a root that fails the oriSolving such an equation, a student clears every denominator at once by multiplying througAn equation contains at least one rational expression, with a variable in a denominator. TTo clear a complex number from a denominator, a student multiplies by the term found by flComplex numbers cannot sit on an ordinary number line, so they are plotted on a plane whosRather than drawing a number line, a student writes the solution set with brackets and parA statement joins two inequalities together in one line, such as 2 < x < 7. That statement