# How do you find the amplitude, period and phase shift for y = cos (x + Pi/4)?

General form of cosine: $y = a \cos \left(b x + c\right)$
Amplitude is equal to $a$, so: $A = 1$
Period: $T = \frac{2 \pi}{b} = \frac{2 \pi}{1} = 2 \pi$
Phase shift: $c = \frac{\pi}{4}$, function is shifted to the left.