Question

Identify the amplitude and the period of the function c(x) = 3cos (x + π).

Answer 1

Amplitude = 3, period = 2 pi

Answer 2

if we call the period T, amplitude A, and phase P
match your equation to
\[ A \cdot cos( \frac{2 \pi}{T} x +P) \]
A is easy, it is 3
to find T, match 2pi/T to the coefficient of x
\[ \frac{2 \pi}{T} = 1 \]
solve for T, to get T= \( 2\pi \)
and, though not asked, the phase is \( \pi \)