Question

What cosine function represents an amplitude of 2, a period of 2π, a horizontal shift of π, and a vertical shift of −1?

Answer 1

f(x) = −1 cos πx + 2

f(x) = −1 cos (x − π) + 2

f(x) = 2 cos (x − π) − 1

f(x) = 2 cos πx − 1

Answer 2

@iGreen @midhun.madhu1987 @hartnn

Answer 3

can you rule out any of the choices?

Answer 4

A and B?

Answer 5

A and B are out. they show an amplitude of 1 (we don't care about the sign of -1)

Answer 6

alright, so whats next?

Answer 7

If you can remember this
if you have cos( A x)
where A is a number
and you want to find the period of cos(Ax)
match up
\[ A= \frac{2 \pi}{T} \]
and solve for T (the period)

in your case, they say
a period of 2π, i.e. T= 2π

so solve
\[ A = \frac{2 \pi}{2 \pi} \]
for A

Answer 8

So how do we get the answer? @phi

Answer 9

Is it D? @phi

Answer 10

Horizontal shift means you'd need to add or subtract pi in the brackets of cos( x + ? )

Answer 11

is it d? @agent0smith

Answer 12

See last post