ANSWER
d. The amplitude is 2
period:
[tex]\frac{2\pi}{3} [/tex]
EXPLANATION
The given function is
[tex]f(t) = - 2 \cos(3t) [/tex]
This function is of the form,
f(t) = a cos(bt)
The amplitude of this function is |a|
where a=-2
[tex] | - 2| = 2[/tex]
The period of this function is given by,
[tex]T= \frac{2\pi}{b} [/tex]
But b=3,
[tex]T= \frac{2\pi}{3} [/tex]
Option D is correct.
