Amistre64, are you out there? I need help! the question is: find the absolute maximum and minimum values of the function in given interval. f(theta)=cos theta -2less than or equal to theta less than or equal to -3pi/4.

- anonymous

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- amistre64

im out here somewhere in the eternal ether :)

- anonymous

Actually, i typed some of that wrong. It's the interval of -2pi less than or equal to theta less than or equal to -3pi/4

- amistre64

its a simple cos function.... nothing modifying it so it should be easy for us to accomplish :)

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## More answers

- anonymous

Just fyi i know NOTHING about converting thetas to square roots.

- amistre64

-2pi to 0 has a max at 0; a max at -2pi and a min at pi
this is just pointing out where the graph bends at between -2pi and -3pi/4 which i went a little far

- amistre64

-2pi = max
- pi = min
and that all you get in that interval

- anonymous

I don't get it. Where are the max and min values in that? I know nothing abou this!

- amistre64

the cosine graph is just a wave that bounces between 1 and -1

- amistre64

at 0 or any even multiples of pi; cos(x) = 1
at pi or any odd multiples cos(x) = -1

- anonymous

How did you figure that out? What is the actual value of the max at -2pi? and -pi? Aren't they like answers in terms of square roots or pi or something?

- amistre64

we could take the derivative which is -sin(x) but that doesnt help out much unless you know the graph for it as well :)

- amistre64

nah; the max of cos(x) = 1
the min of cos(x) = -1

- amistre64

cos(-2pi) = 1
cos(-pi) = -1

- amistre64

thats just the definition for cosine...

- amistre64

Dx(cos(x)) = -sin(x)
-sin(x) = 0 at..... -2pi, and -pi in between [-1pi,-3pi/4]

- anonymous

Ok, here's how they want the answer and I can't figure out what you are telling me. They want "Absolute maximum is ____ at theta=_____

- anonymous

Then "Absolute minimum is ____ at theta=____"

- amistre64

##### 1 Attachment

- amistre64

absolute min = -1 at -pi

- amistre64

absolute max = 1 at -2pi

- anonymous

Bless you, dear. But HOW DO YOU KNOW THIS? is there a table of values? I just started this in calculus, and I am sure i will need it in the future, and unless you want to take my next calc exam... seriously where i find the equations for this? Like what does sin(5pi/3 equal? Where do I find those values or is there a conversion with a formula?

- amistre64

its from trig class; trig is just memorizing angles and sin cos tan stuff

- anonymous

ok but where do you find the angles to memorize? Like i said, is there a table or something? A formula? What? there has to be some way to figure this out!!!!!

- amistre64

yeah, look up 'trig tables' and 'trig graphs' in google; theyll give you alot to pick from :)

- anonymous

ok, btw, not that you doubted your brain power or anything, but of course you were right and figured out in 3 seconds what i have been trying to figure out for literally 43 hours. 1 problem...3 hours??? I can't do that for 50 problems!!! These tables will help?

- anonymous

i did not mean 43 hours, i meant 3

- amistre64

:) they will help. And when i dont use trig for a while im bound to forget them ;)

- anonymous

do you do this math stuff for fun? because you love it so much? you must because you don't get paid to help dummies like me!!! ; )

- amistre64

lol... i do enjoy math; its the one constant in my life :)

- anonymous

yay for you. i enjoy it too, more on the algebra end, but i am not good at it naturally; I struggle to learn it. Trying to take a calc course online is like literally teaching myself everything there is to know about calc! Not sure I will be as successful as you are at it!

- amistre64

ive taught myself up to about calc4 so far; its easy once you get past the tedium of limits and longhand version of derivatives and integrals

- amistre64

well, derivatives are pretty straight forward; integrals can be tricky because its more art than science

- anonymous

oh my gosh. I could only wish to be that smart! Thank you so much! I don't know wht time it is there, but it is almost 3 am here in Illinois and I have to be up with the kids in like 3 hours1 This math will literally be the death of me! Thank you thank you thank you again and again! I'm sure i will talk to to you VERY soon. Rachel.

- anonymous

Good night, and thanks again.

- amistre64

Nite , im in florida ;)

- anonymous

So its like almost 4 am there!

- amistre64

illinois is one of them mormon states i believe

- amistre64

330am if the computer is right ;)

- anonymous

yes it is it's 2:30 here. crazy!

- anonymous

ttyl, thanksoncemore

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