Which cosine function has maximum of 4, a minimum of -4, and a period of 2pi/3?

Question

A. y=4 cos 3 theta
B. y= 4 cos 2 theta/3
C. y=4 cos theta/3
D. y=4 cos 3 theta

Answer 1

Write the equation as
y=a cos(b(θ))+k

For a max=4,and min=-4, k=0, and a=4, so
y=4cos(b(θ)))

Period = 2π/b
if period = 2π/3, then b=3, and the equation reads:
y=4cos(3θ)

Pick your choice betwen A and D, unless there is a typo.

Answer 2

which one is it though

Answer 3

it's D. y=4 cos 3 (theta).
the answers given in the original question are the same for A and D

Answer 4

thanks

also Advil is better
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