Cos Definition and 317 Threads

Homework Statement Find the integral f(x) = x^3 sqrt(x^2 + x^8 + 8) cox(x) dx The Attempt at a Solution I need help starting. It appears to be either integration by parts and/or substituion.

Homework Statement At an airport, you pull a 18-kg suitcase across the floor with a strap that is at 45 degrees above the horizontal. Find the normal force and the tension on the strap, given that the suitcase moves with a constant speed and the coefficient of kinetic friction is 0.38...

Erm, I have this integration question: sqrt((1-cos(x))/2) with an upper limit of 2pie and lower limit of 0. I can't seem to do it right. I tried simplifying it: sqrt((1-cos(x))/2) = ((1-cos(x))/2)^(1/2) = 1 - (cos^-2(x))^(1/2) = 1 - cos^-1(x) Then I intgrated 1... which becomes...

a wave equation is given as A = A cos (kx - ωt) so why if someone describes the wave equation to be A = A sin (ωt - kx) , the argument of the sin function changes by a minus sign? and is there a meaning to it? also i still don't really understand why the minus sign in the first equation...

Homework Statement Show that sen² 25º + cos² 45º + sen² 65º = 3/2 Homework Equations cos 45º= 1 The Attempt at a Solution I get confused with the ² on the cos and sen...

Homework Statement Find y such that cos y=cos(90+y) and −90degrees <= y <= 0degrees?Homework Equations cos(a+b)=sin(a)cos(b)+cos(a)sin(y)The Attempt at a Solution This is a question that came up in my linear algebra class. We just learned about dot product, but this doesn't seem like it's...

Can anyone give any hint to solve this ? If sinx + sin2x + sin3x = 1, then , cos6x - 4cos4x + 8cos2x = (a) 1 (b) 4 (c) 2 (d) 3

Homework Statement express cos^4 x in terms of cos 4x and cos 2x given that cos^ x = 0.5(1 + cos 2x) The Attempt at a Solution i did some playing around for a minute and came to this; cos^4 x = 0.25 + (cos2x)/2 + (cos 4x +1)/8 and thought, great! now i'll just check it on...

Homework Statement The limit of Cos X as x approaches one using the formal definition. Given epsilon values of .1, .001, .00001 Homework Equations The Attempt at a Solution Spent all period in physics calc trying to solve this using the formal definition. Since there is no...

[b]1. Homework Statement [/b Determine whether the function D=A sin kx cos \omegat is a solution of the wave equation. Homework Equations D=Asin (kx-\omegat) The Attempt at a Solution sorry completely lost please help

if \mu = cos(\theta) and \mu_{0} = cos(\theta_{0}) and cos(\pi - \Theta) = \mu_{0}\mu + \sqrt{1-\mu_{0}^{2}}\sqrt{1-\mu^{2}}cos(\phi) Then cos(\pi - \Theta) = cos(\theta_{0})cos(\theta) + sin(\theta_{0})sin(\theta)cos(\phi) Is this not correct?

http://www.berkeleyscience.com/maxwells.htm """""When a conductor (a wire) is placed in an electric field, the field may induce a voltage in the conductor. The diagram shows an electric field in the x direction with magnitude E. If the conductor is perpendicular to the E field, there is no...

Can I get the integral of cos( t^2/2)?

ok ... here's my problem i need to prove that the LHS = RHS sin^2 + 2cos - 1 / 2 + cos - cos^2 = 1 / 1 + sec i tried to use the pythagarean identies and substitute the 1 and 2 but tht isn't getting me anywhere .. please help

Homework Statement -log5(cos(x)) = -1/2 How many answers are there in the interval [0,2pi) The Attempt at a Solution 5^-1/2 = cos(x) 1/sq rt 5 = cos(x) sq rt 5/5 = cos(x) 0.447 = cos(x) x = 63.43 Basically, I have no clue how to find the number of answers in the interval ; ( I...

A wire has a current given by i (t ) =15 2 cos (2π 60t ) [A]. Determine how many electrons cross a particular point on the wire, moving from right to left, in the time interval 0 < t < 0.001I don't get this one. What equation do Ineed to use? I can't find the right one, but it seems so easy...

Homework Statement \int_{0}^{\pi} \cos ( \sin x ) \mbox{d}x The Attempt at a Solution If I use u = \pi-x I get : \int_{0}^{\pi} \cos ( \sin x ) \mbox{d}x = \int_{0}^{\pi} \sin ( \cos x ) \mbox{d}x but then what?

Homework Statement plot using matlab: g = 3 cos (10pi t) convolved with 4 impulse (t +0.1) Homework Equations The Attempt at a Solution x = -10:0.1:10; u = 3*cos (10*pi*x); v = 4*dirac(x + 1./10); y = conv (u,v); plot (x,y); but i keep getting this error: Error using ==>...

Homework Statement i have to create a mathematical forumal from data of high and low tide depths and times. from that predict the next weeks outcome. it has to have sin or cos in the equation. a*COS (bx+c)+d or sin. this is the data given Mon 09/03/2009 Tue 10/03/2009 Wed 11/03/2009...

Hi I was wondering if there is a non-numericla way to solve the following equation: 144 - 90sin x - 155.8cos x = 0 Thanks

The displacement, x= Acos(\varpit+\phi), repeats for every increase in 2pi. Why can't I make the above equal to Acos(\varpit+\phi + 2pi), and divide by cos. This gives \phi]=0. This is clearly wrong. Why? And how does angular frequency apply to a mass on a spring anyways, it doesn't move in a...

Homework Statement Compute \int^{\pi/2}_{0} \frac{sin^{2009}x}{sin^{2009}x + cos^{2009}x} I used the identity cos^{2}= 1 - sin^{2}, but instead I set the exponent as 2009. And so I ended up with the answer being -1. I'm just wondering whether this is a legal solution or am I not allowed to...

Homework Statement Ok so we started Fourier Analysis in circuits. How can i tell the Period of a function that's let's say sin(2t)+3cos(5t) something like that . Any help or url's that have information on this

Homework Statement \int^{0}_{1}\frac{x^{2}}{\sqrt{1-x^{2}}} Homework Equations The Attempt at a Solution Let x=sintheta dx=cos theta \int^{0}_{1}\sin^{2} Now I get stuck

Hi, I get really confused when to use the cos function or the sin function. for example, I was looking at this yesterday and thought the other way around of the correct answer. Why did it chose sin function for tension and cos function for the normal force? This problem doesn't explain why it...

First of all, hi I'm new here my name is crisanna. I stumbled upon this site across the web and realized this 's a great site! Anyway , here 's my question. Does anyone know how to integrate sin (1 +cos ^2 x) ? I tried the method integrate by parts but I got stucked. Below is my attempt : u=...

Homework Statement how could i prove that cos x= sum (n=1 to 00) [((-1)^n) * x^(2n)/((2n)!)] is continuous and differentiable at each x in R Homework Equations the Taylor Expansion of cosine is the given equation The Attempt at a Solution basically i need to prove that the...

Homework Statement Im wondering if this question could be solved. Given that sin theta =a+b and cos theta =a-b Find tan theta when a/b=3 Solved alr.. the ans is 2. Homework Equations The Attempt at a Solution

Homework Statement I can not determine the solution to the diff. eq. Homework Equations \ddot{x}+k \cos{x}=0. The constant k is postive. The Attempt at a Solution I tried solving it with the methods I know and it all ended up in a big mess. I am just not used to the second...

Is there some mathematician who knows the "core reason" why exp() is connected with cos()? I mean I'm confident with "advanced maths for physicists", but maybe some abstract theory gives an answer to this. I was think of something like: |e^{i\phi}|=1 therefore it's a unit circle. But also...

Homework Statement I have been given these two equations: x=2acos^2(x) , y = 2a(cos(x))(sin(x)) where a ranges from 0 to 5 and -2π < x < 2π I need to prove that these equations (when you plug in values for x) create points that when plotted, give you a circle with center (x-a) and radius a...

How do I solve: [sin (pi/3)] + [cos (pi/6)]? <--- "pi" is 3.14... I think that [sin (pi/3)]= (square root 3) divided by 2 AND that [cos (pi/6)]= (square root 3) divided by 2. Now I can't remember how to add fractions containing square roots. My textbook...

f(x)=x4 cos(2/x6) g(x) <= f(x) <= h(x) how to get g(x) and h(x) by using the squeeze theorem?? I know is something like this -1 <= x <= 1 But how do i implement it here, and especially to the cos, sin, and tan??

Hi. I believe this may have been addressed previously but I wanted to make sure since I don't think it was completed. Hi I know that differentiating sin = cos , and differentiating cos = -sin. Time to prove it. [SIZE="4"]Q3: Prove that: \frac{d}{{dz}}\sin z = \cos z We know the...

I'm working through Kline's Calculus book, and am at the chapter on Integration on Differentiation of Trig Functions. A question asks to find the derivative of: (I've labeled all equations for easy reference) (1) y = sin x * cos x unlike the solution guide which advocates using the product...

[SOLVED] Integral of Square of Reciprocal of √(a + cos t) Homework Statement Demonstrate that \int_0^\pi \frac{dt}{(a + \cos t)^2} = \frac{a\pi}{(\sqrt{a^2 - 1})^3} where a > 0. The attempt at a solution I want to compute this using the Residue Theorem. The first thing I did was...

Homework Statement Integrate \int\sin 6x + 3\cos 5x dx Homework EquationsThe Attempt at a Solution The way I was taught was the 'u' substitution method. I know that \int\sin u du = -\cos u + C and I know that \int\cos u du = \sin u + C Here's what I've done so far \int\sin 6x + 3\cos 5x...

I've started to work on the it, just tell me if I'm on the right track. cos (45-30) = (\sqrt{3} + 1) / 2\sqrt{2} so cos 15 is irrational. cos3x = 4cos^3x - 3cos x \Rightarrow cos 5 is irrational cos 4x... cos 20 If this is a bad way, maybe someone knows a better one. Here is what I think...

TRIG~ Law of Sin - Law of Cos HELP PLZ! hey i need some help... so umm please help me

[SOLVED] Trigonometry cos A + 1 My little sis needs help w/ the following problem for her homework and to tell you the truth, aside from the fact that I'm too busy I have no idea how to explain this to her step by step. I would appreciate an explanation on how to solve it -- a solution would...

How can there be three forms of the double-angle formula for cos 20?

Im having an issue of when to use Cos and Sin. When calculating Force (Normal and Frictional) with multiple demension problems you are typically given the angle of the incline. When trying to calculate for Fgx (or basically x) I would think to use cos(theta) and when dealing with Fgy (or...

Homework Statement Calculate for x\in(0,\pi/2) \lim_{N\rightarrow\infty}\prod_{n=0}^{N}cos(\frac{x}{2^{n}}) Hint: Use the Double-Angle Formulas for the sine. Homework Equations The Attempt at a Solution cos(x)\cdot cos(\frac{x}{2})\cdot cos(\frac{x}{4})\cdot... \frac{\sin2x}{2\cdot\sin...

This is only part of my question and I need the answer to continue, when does cos x = -x? on my calculator it is -.7390... isn't it supposed to be a nicer number ie pi over something?

ok so I have the problem ycos(x^2)dxdy with parameters dx=y^2 to 1 and dx=0 to 1 the first problem I have is integrating cos with respect to x^2. is it a double angle identity? the second is how do I go further if Y^2 gets added into the mix later? The attempts I have made have made me even...

Homework Statement Evaluate the limits that exist: lim x->0 of \frac{1-cos4x}{9x^{2}} Homework Equations lim x->0 \frac{1-cosax}{ax} = 0 The Attempt at a Solution so far I've got this \frac{4x}{9x^{2}}\frac{1-cos4x}{4x} The second part has a limit of 0 but I don't know what to...

Im doing a differential equation and end up with my last step, which is an integration. I can't seem to remember how to integrate this one int. (tanx)/(1-cosx) hmmm [(sinx)/(cosx)] / (1-cosx) u = cosx du = -sinx dx throw a negative outside the integral...

First off, thanks for your help. I feel like a dope because everything I'm doing looks correct to me, but my answer is not the same as the book or solution manual gives! I'm usually so good at finding my mistakes. Thanks for taking the time to help. Homework Statement...

My teacher told me that C sin(k x) + D cos(k x) = F sin(k x+gamma) if neither C nor D is 0 (gamma is a phase angle). How do you derive the expression on the right of the equal sign from that on the left?

Homework Statement can som1 please give me an idea where to start with this integral. integral of: cos (2t) x e^2t thanx Homework Equations The Attempt at a Solution