How do you find the period and amplitude of y=2/3cos((pix)/10)?

1 Answer
Mar 29, 2017

amplitude is 2/3
period is 20

Explanation:

y=alpha*cos(x) period is given as (2pi) and amplitude is alpha
for y=cos(ax), period is given as (2pi)/a
here, y=(2/3)cos(pi/10)x
so period is (2pi)/(((pi)/10))=20

also, amplitude is 2/3, because the maximum deviation of curve from the mean is 2/3 at cos((pix)/10) = 1

graph{(2/3)cos((pix)/10)[-10, 10, -5, 5]}