Question

Use the graph below to answer the question that follows:

trig graph with points at (0, 0) and pi over 2, 3 and pi, 0 and 3 pi over 2, negative 3 and 2 pi, 0 and 5 pi over 2, 3 and 3 pi, 0

What trigonometric function represents the graph? (6 points)
f(x) = 3 sin(x − pi over 2 )
f(x) = −3 sin(x − pi over 2 )
f(x) = −3 cos(x − pi over 2 )
f(x) = 3 cos(x − pi over 2 )

Answer 1

By graphing the given points, we will get the attached figure
which represents:
                                          f(x) = 3 sin x
but sin x = cos (x - π/2)
                                     ∴  f(x) = 3 cos ( x - π/2 )

The correct choice is option ⇒⇒⇒ f(x) = 3 cos(x − pi over 2 )