# How do you find the amplitude and period of y=2cosx?

The amplitude is <-2;2> the period is $2 \pi$.
The basic amplitude of a cosine is <-1;1>, if you multiply the function by a number the amplitude of a function is also multiplied, so the amplitude of $y = 2 \cos x$ is <-2;2>.
The basic period of a cosine is $2 \pi$ and it would change if there was a coefficient in front of $x$ in a formula of the function.