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Trigonometry Basic trig question - finding the period of a sinusoid

DeusAbscondus

Active member
Jun 30, 2012
176
Would someone kindly take a look at my geogebra snapshot attached,
and tell me a more formal way of representing the formula for the period of a trig function of form:

f(x)=Acos(bx)$$
where A is amplitude and b is period

Thanks,
D'abs​
Attached Thumbnails


PS: sorry about sloppy maths: been away for months and seem to have forgotten use of $$ to wrap around text to create latex;
 

MarkFL

Administrator
Staff member
Feb 24, 2012
13,775
Re: basic trig question

I would say you are confusing period with angular velocity.

If given the sinusoid:

\(\displaystyle f(t)=A\cos(\omega t)\)

then the angular velocity is $\omega$ and the period $T$ is:

\(\displaystyle T=\frac{2\pi}{\omega}\)

since we may write:

\(\displaystyle f(t+T)=A\cos(\omega(t+T))=A\cos(\omega t+2\pi)=A\cos(\omega t)=f(t)\)
 

DeusAbscondus

Active member
Jun 30, 2012
176
Re: basic trig question

I would say you are confusing period with angular velocity.

If given the sinusoid:

\(\displaystyle f(t)=A\cos(\omega t)\)

then the angular velocity is $\omega$ and the period $T$ is:

\(\displaystyle T=\frac{2\pi}{\omega}\)

since we may write:

\(\displaystyle f(t+T)=A\cos(\omega(t+T))=A\cos(\omega t+2\pi)=A\cos(\omega t)=f(t)\)
Thanks kindly Mark.
This clears up my query.
(I also just realized why my $$s aren't working: i have re-installed OS and have yet to re-install a Tex program)
 

Jameson

Administrator
Staff member
Jan 26, 2012
4,043
Re: basic trig question

Thanks kindly Mark.
This clears up my query.
(I also just realized why my \$\$s aren't working: i have re-installed OS and have yet to re-install a Tex program)
If you're referring to your original post then I believe you just forgot the opening pair of dollar signs. You wrote: f(x)=Acos(bx)\$\$ but you need to write \$\$f(x)=Acos(bx)\$\$ and it will output:

$$f(x)=Acos(bx)$$

Hope this helps! :)