Use the appropriate sum or difference identity to write the given expression as a function of x alone.
-sin (270° - x)
A) cos x
B) sin x
C) - cos x
D) - sin x

Question

Quizplus · Accepted Answer

The sum and difference identity for sine, sin(A - B) = sinA cosB - cosA sinB, can be applied here with A = 270° and B = x. Since sin(270°) = -1 and cos(270°) = 0, the expression simplifies to -cos(x), making the correct answer - cos x.

Use the Appropriate Sum or Difference Identity to Write the Given