By what factor is the graph of the trig function stretched?

Trigonometric ratios and functions, the unit circle, inverse trig functions, identities, trig graphs, etc.
chiefboo
Posts: 8
Joined: Fri Mar 22, 2013 3:46 pm
Contact:

By what factor is the graph of the trig function stretched?

Postby chiefboo » Thu Jun 06, 2013 8:25 pm

y= 2 - (5/2) sec( (2pi/5)x-4pi)

By what factor is the graph of this secant function being stretched horizontally?

I thought you're supposed to divide 2pi by 2pi/5:

2pi/(2pi/5)=

2pi * 5/2pi =

10pi/2pi = 5

The correct answer was 2pi/5

Please help me understand this. I have a unit exam next week and a quiz I need to be studying for tomorrow.

jg.allinsymbols
Posts: 72
Joined: Sat Dec 29, 2012 2:42 am
Contact:

Re: By what factor is the graph of the trig function stretch

Postby jg.allinsymbols » Fri Jun 07, 2013 12:28 am

Yes it is stretched or DIVIDED by 2*pi/5.

Actually squeezed by factor of 2*pi/5. The period is shorter.

User avatar
stapel_eliz
Posts: 1733
Joined: Mon Dec 08, 2008 4:22 pm
Contact:

Postby stapel_eliz » Fri Jun 07, 2013 2:37 pm

chiefboo wrote:y= 2 - (5/2) sec( (2pi/5)x-4pi)

By what factor is the graph of this secant function being stretched horizontally?

I think the confusion here lies in that you're (quite sensibly) trying to find the period, while the question is asking "by what factor is the [period] being stretched?" So you're correct that the period is "5", but this period is created by "stretching" the regular period of by a "factor" of .

That is, you did the following:

. . . . .

...where "B" is the value multiplied against the variable inside the trig function. On the other hand, I think the question is looking for:

. . . . .

...where "F" is the "factor" they're wanting.

Yes, it's confusing.


Return to “Trigonometry”

cron