Question

can someone please help me graph 3cos(4x+pi)-1
I'm stuck!!

Answer 1

A=3
B=4
C=pi
D=-1
A=amplitude
B = how many cycles will complete in 2pi
D= vertical shift + is up. - is down

4x+pi is bound between 0 and 2pi
0< 4x+pi < 2pi
solve
subtract pi from all three and get
-pi< 4x < pi
divide all three by 4 to isolate x and get
-pi/4 < x < pi/4
the left and right values are where your cycle starts and ends so there was a left shift of pi/4.
your period is calculated by right end minus left end:
pi/4 - -pi/4 = 2pi/4 = pi/2

Answer 2

okay. I understand that, so what would the point be at -pi/4
would it be 3?

Answer 3

on your graph -pi/4 is where the graph of the cycle starts
label x axis -pi/4 -pi/8 0 pi/8 pi/4
start cross x peak cross x end

Answer 4

okay, what about for the y axis? would it be 3,2,1

Answer 5

yes, amplitude of +3 to -3

Answer 6

be careful, is it asking you to graph one cycle or graph between 0 - 2pi?

Answer 7

I have to graph two cycles

Answer 8

ok the x coords I gave covers the 1st one, you can come up with the others?

Answer 9

yuup!! :) Thank you so much for helping me!! :)

Answer 10

you bet!