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anonymous
 5 years ago
for what value of on the interval (9.65, 11.28) will f(x) take on a minimum if f(x)=−7.2sin(0.3x)+1.8cos(0.3x). What is f(x) at this x value? Same question for the maximum on the same interval.
anonymous
 5 years ago
for what value of on the interval (9.65, 11.28) will f(x) take on a minimum if f(x)=−7.2sin(0.3x)+1.8cos(0.3x). What is f(x) at this x value? Same question for the maximum on the same interval.

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anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0this should say for what value of x on the interval... Sorry!

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0deriving trig...aint had to do this yet :)

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0well the derivative is 0.54sin(0.3x)2.16(cos(0.3x) if you need it. I know I need to set it to zero to get the critical values, but I don't know how to solve for x lol

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0Dx(7.2 sin(.3x)) = 7.2(.3) cos(.3x)

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0lol .... I was getting there :)

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0lets multiply by 100 to get rid of some of those decimals

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.054 sin(.3x)  216(cos.3x) = 0

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0can we factor out anything from 54 and 216? I know 2 comes out...

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0you can take out a 9 i think

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.054/216 = 27/108..try 3 now 9/36 try 3 again 3/12 and 3 again 1/4

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0looks like 54 factors out completely... 216/54 = anything useful? 4 yay!!

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.054(sin(.3x) + 4cos(.3x)) this look right to you so far?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yeah I'm following I think. lol, that's what I have when I do the same work on my calculator. :)

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0so, lets see what sin(.3x) + cos(.3x) gets us to equal 0

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0they gotta be opposites of each other, so lets throw one to the other side

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0and dont forget that 4 that I left out lol

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yeah i was going to ask why we weren't using it, lol but nevermind

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.04cos(.3x) =  sin(.3x) now picture these graphs for a minute

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0the cos is just stretched 4 tall, so the 4 doesnt matter the sin is flipped over upside down

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0.3 = the frequency of the graphs

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0these cross points at 2 places every time they go thru one frequency...does that make sense?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0once in Q2 and another in Q4

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0the only angle that has sin and cos equal is 45 degrees

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0right.. I put them in my graphing calculator. lol so that means I have more than one answer right?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0yes... more than one answer, and it will have something to do with 45 degrees

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.09.65 and 11.28 is our interval

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0I might be wrong about the 45 tho :)

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0derive it again to see if we can get some useful information...

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0derive the original f(x) or take the second derivative?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0second derivative will give us a better picture....

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.064.8 sin(0.3 x)16.2 cos(0.3 x)

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0I got: y'' = .648 sin(.3x)  .162 cos(.3x)

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0oh, yeah I just had it multiplied by 100 still

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0it might be helpful, but im still "stuck" :)

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0When I asked a friend, she told me I needed to use the quadratic. However, she had her math major friend do the problem for her, and can't tell me anything farther than that lol

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0lets go back to the original.. sin(.3x) + 4cos(.3x)

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Is there a way for us to write them both in the same terms, like a way for us to make cos to sin?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0there can be a square root involved, or a phase shift....

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0If it helps, when I tried using wolfram alpha, it gives me the answer.. x = 20/3 (pi n+tan^(1)(1/4 (1+sqrt(17))))

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0But I don't actually even know what that means, lol so I that wasn't very helpful either. It was kind of a a last resort as it was, because my assignment is due at midnight. :\ lol

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.04cos(.3x) = sin(.3x) square both sides to get 16cos^2(.3x) = sin^2(.3x) 16cos^2(.3x) = 1  cos^2(.3x)

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0then: 17cos^2(.3x) 1 = 0 right?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0i believe you're correct.

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0cos(.3x) = sqrt(17)/17 then ....if that helps :)

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0okay so x ends up being like 4.419392212

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0cos1(sqrt(17)/17) is?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0cos1(sqrt(17)/17) is 1.325817664 i think

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.025.32 is what I get for that x :) does that make any sense?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.025.32 radians of course

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0ohh.. so why am I getting a different number, is my calculator just in the wrong mode?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0maybe; and I used 1/sqrt(17) to be simple

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0lets plug that in to see what we get: sin(.3(25.32)) + 4cos(.3(25.32)) :=: 0 ??

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0I'm not getting zero. :\

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.00.1321 + 3.9648 = .... ack!!! lol.

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0need someone smarter than me I guess :)

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0oh no. lol what do I do now? Do you have any ideas of where else I can get help b y midnight?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0how many points it take off if it is wrong?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0I'm not sure.. there are only 4 sections and this one is technically two parts.

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0let me review our stuff for a few minutes and see what I can deduce...

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0alright. If it helps, on the thread for the problem, it says to take the derivative equal to zero, and that you should get tan=#, then take the inverse.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0I don't know how they're getting tangent though.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0What if we divided both sides by cos(0.3x) and then had tan(0.3x)=4.. does that work?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.04x y=0...y=4x....y/x = 4 4x +y = =..... y=4x......y/x=4 this is the tan they get at.... sin(.3x)  = 4 cos(.3x) sin(x) = sin(x) so thats the same

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0tan(a) = 4 tan1(4) = what?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0i was getting to it.... :)

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.075.96 degrees is a divide that by.3

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0so we have 253.212=x ?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0that sounds large. lol

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0remember that tan1 spits out an angle between 90 and 90

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0(75.96 + 180) /.3 ?? maybe

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0that one gives us 46.8

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0i see that..... maybe our interval itself gives us a max or min at the end points?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0if you put those in.. for 9.65, we get 0.0119783705 and for 11.28, we get 0.190832377

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0.3x gives us one cycle every 20pi/3 does that helps us out?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0well in the wolfram alpha, it said something about 20/3 pi * n, but n is supposed to mean any integer, so I didn't really understand it.

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0n = the angle measurement a normal cycle is 2pi but we disturb that with .3.... so it increases the frequency of the cycle to 20pi/3

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0x = 20/3 (pi n+tan1(1/4 (1+sqrt(17))))

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0What is the value of our interval in terms of pi?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0x(pi) = 9.65 x = pi/9.65

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0.325 pi to .279 pi right?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0that aint gonna make a difference, becasue our interval is telling us the value of "x" which is the angle involved.... not the period....

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0okay.. I'm just lost at this point. lol I really don't even know how to get any further in this.

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.0im at a loss for the moment as well :) its all those decimals that are messing me up

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0I've got it!!!! lol I graphed it and just followed the graph and put in the numbers :P thanks though hahah
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