Question

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.

Answer 1

im out here somewhere in the eternal ether :)

Answer 2

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

Answer 3

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

Answer 4

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

Answer 5

-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

Answer 6

-2pi = max
- pi = min

and that all you get in that interval

Answer 7

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

Answer 8

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

Answer 9

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

at pi or any odd multiples cos(x) = -1

Answer 10

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?

Answer 11

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

Answer 12

nah; the max of cos(x) = 1

the min of cos(x) = -1

Answer 13

cos(-2pi) = 1

cos(-pi) = -1

Answer 14

thats just the definition for cosine...

Answer 15

Dx(cos(x)) = -sin(x)

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

Answer 16

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=_____

Answer 17

Then "Absolute minimum is ____ at theta=____"

Answer 18

absolute min = -1 at -pi

Answer 19

absolute max = 1 at -2pi

Answer 20

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?

Answer 21

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

Answer 22

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!!!!!

Answer 23

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

Answer 24

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?

Answer 25

i did not mean 43 hours, i meant 3

Answer 26

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

Answer 27

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!!! ; )

Answer 28

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

Answer 29

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!

Answer 30

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

Answer 31

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

Answer 32

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.

Answer 33

Good night, and thanks again.

Answer 34

Nite , im in florida ;)

Answer 35

So its like almost 4 am there!

Answer 36

illinois is one of them mormon states i believe

Answer 37

330am if the computer is right ;)

Answer 38

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

Answer 39

ttyl, thanksoncemore