What is Cos: Definition and 318 Discussions

Cos Cob is a neighborhood and census-designated place in the town of Greenwich, Connecticut. It is located on the Connecticut shoreline in southern Fairfield County. It had a population of 6,770 at the 2010 census.Cos Cob is located on the western side of the mouth of the Mianus River. The American Impressionist Cos Cob Art Colony flourished in the late 19th and early 20th centuries. An offshoot of the group, the Greenwich Art Society, continues to support local artists in town.
The town of Greenwich is one political and taxing body, but consists of several distinct sections or neighborhoods, such as Banksville, Byram, Cos Cob, Glenville, Mianus, Old Greenwich, Riverside and Greenwich (sometimes referred to as central, or downtown, Greenwich). Of these neighborhoods, three (Cos Cob, Old Greenwich, and Riverside) have separate postal names and ZIP codes. From 1883 to 1885, the official post office name of Cos Cob was Bayport.
In 2015, Forbes ranked Cos Cob the 287th wealthiest place in the US with a median house sale price of $1,329,107.

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  1. S

    Torque when to use cos and sin

    I have a issue with determining when to use cos and sin when calculating torque; For example. Referring to the attached picture. The SEESAW asks evaluate the torque of m2 (m2>>m1). For second part evaluate the torque... MY question: WHY in the first part (SEESAW) do they use cos...
  2. M

    MHB Solving a Trigonometric Equation for Cos (x)

    Hi, may you help me? I have a question I solved but couldn't ended. If cos(x)+5Sec(x)=1.1 then Cos(x)=? 2Cos(x)+5Sec(x) =11/10 2Cos(x)+5/Cos(x)=11/10 2Cos(x)*Cos(x)+5=11/10*Cos(x) 2Cos^2(x)+5=11/10*Cos(x) 2Cos^2(x)-11/10-Cos(x)-5=0 then i used delta=b^2-4ac then i found delta=-4.79...
  3. S

    Laplace's equation & Fourier series - I can use cos or sin?

    Homework Statement This is a question related to finding the velocity field of an incompressible fluid in a square pipe with sides at y = ±(a/2) and x = ± (a/2). It comes down to solving a homogenous equation which is also Laplace's equation \frac {δ^2 w(x,y)^H}{δ x^2} + \frac {δ^2...
  4. M

    Finding cos in radians without calculator? Help?

    Hey guys this question is going to sound pretty dumb, but I never learned how to do this. What if I want to find say, cos(pi/5) but I don't have a calculator? Even if I did have a calculator, I want it in nice values, like square roots, rather than decimals anyway. If I have something...
  5. C

    Where do "Other" Frequency's Come From when Multiplying Cos Waves?

    When you multiply two cos waves together, where do all the "other" frequency's come f When you multiply two cos waves with similar frequency's you get a graph that looks like this: http://www.wolframalpha.com/input/?i=%28cos%282*pi*0.8*x%29%29*%28cos%282*pi*0.9*x%29%29 With equation...
  6. D

    Trig sin and cos graphs n00b help.

    Homework Statement Hi everyone. I understand the basics of trig graphing; but am having a hard time understanding f(x) first of all what to f and x stand for? Above and beyond that any help understanding f(x) or a link to a website that might help me would be great. Homework Equations...
  7. H

    Forced Harmonic Oscillator C Cos wt dC/dt = 0

    I believe this is pretty standard. Given a mass m on a spring with spring constant k, a solution to the second order differential equation of motion m\ddot{x} = -kx, is x = cos ωot, and ωo = \sqrt{k/m}. If that same oscillator is driven with a force F(t) = Fo cos ωt the equation of motion...
  8. A

    MATLAB Solving DFT of Cos Function Issue with MATLAB

    greetings, i have typed some code in MATLAB to find the 5 point fft of cos function of frequency 100hz but in answer i am not geting the answer at 100 hz.may i know where the things going wrong. the code is as this one clc; t=0:1/4:1; x=cos(2*pi*100*t); xm=abs(fft(x)); disp(xm)...
  9. L

    Finding this limit involving sin and cos

    Homework Statement I have this function: f(x) = \frac{1}{x}-\frac{\cos{(x)}}{\sin{(x)}} For all x \in R where x \neq n \pi, n \in Z Ok I have to find the following limit: lim_{x\rightarrow0+}(f(x)) Homework Equations Limits in general and perhaps the always great...
  10. P

    Solving integral - gaussian distribution of cos

    Homework Statement I have to prove: ∫(-infinity:infinity) cos(pi*v/2L)*e^-((L-L_av)^2/sqrt(2pi)*sigma^2) dL proportional to cos(pi*v/2L_av)*e^-(t/tau)^2 tau is some constant, and sigma << L_av. The Attempt at a Solution i can change the integral to 0:infinity, since sigma <<...
  11. S

    Is there an identity for the cos( 1/3 x ) ?

    It seems that this term comes up in solving the cubic equation. While there is the identity for the half-angle, there doesn't seem to be one for third-angle.
  12. S

    (1 + cot + tan )(sin - cos ) whole upon sin^3 - cosec^3

    (1 + cot + tan )(sin - cos ) whole upon sin^3 - cosec^3 = sin^2cos^2 prove this . ( assume theta is front of all functions ) , i don't know where to start :/
  13. M

    Prove problem involving sec cos sin

    Hi guys been struggling to solve this If you know how to do it, please do solve and show work so that I can follow your steps Homework Statement prove (sec(x)-cos(x))/(sec(x)+cos(x))=(sin^2(x))/(1+cos^2(x))
  14. S

    Solving Sin (90+Theta) = Cos - Explanation

    i understand how sin90-theta is cos , but i am having trouble with sin 90+theta = cos ...please explain
  15. K

    Solve -sin 20° sin 40° sin 60° sin 80°sin 20° cos 30° sin 40°

    Solve - sin 20° sin 40° sin 60° sin 80° sin 20° cos 30° sin 40° cos 10° hmm...?
  16. L

    Linear independence of sin (x), cos (x) and 1, proof

    What would be the best way to show that functions f(x)=1, g(x)=sin(x) and h(x)=cos(x) are linearly independent elements of the vector space \mathbb{R}^{\mathbb{R}}? I know that the linear independence means that an expression like \alpha \mathbb{x}_1 + \beta \mathbb{x}_2 + \gamma \mathbb{x}_3...
  17. M

    Understanding the Differentiation of the Cos Law Equation

    I'm struggling here as I've not done diferentiation in a few years. The cos law states: c=(a2+b2-2abcosθ)1/2 I'm trying to figure out how to differentiate this, so if c were a length, what the velocity with which c grows as θ increases (ie c dot) Any pointers would be great! If its easier, a...
  18. S

    Question about tan, cos, and sin

    So, I am trying to understand what tangent, cosine, and sine are in practical terms e.g. if something is tangent with something else we know it is touching that something. That seems like a practical definition of tangent to me. So, then what is a sine? what is cosine? I was thinking like...
  19. G

    MHB Solving for postive value of x when cos (60)

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  20. U

    Identities sin, cos, tan etc. stuff

    Homework Statement ((cos x)/(1+sin x))+((1+sin x)/(cos x)) Homework EquationsThe Attempt at a Solution multiplied the left equation by (cos x)/(cos x) and the right fraction by (1+sin x)/(1+sin x) get ((cosx)^2 +(1+sinx)^2) / (1+sinx) (cos x) and I have no idea where to go from here
  21. T

    Frustrating excel problem with COS

    Dear all, I am currently using excel to work out some values for incident solar radiation but I am running into a rather frustrating problem when I try to do the following: =COS(9.863) my calculator tells me correctly this is 0.985. however, when I put this in excel it decides it...
  22. B

    Understanding the Derivative of ln(cos x) for Plane Curves?

    Homework Statement the question is for plane curves. find T N and k for the plane curves 1. r(t) = ti + ln (cos t) the derivative of ln x is 1/|x|, so why isn't the derivative of ln cos x, 1/cos x or sec x? My book says the answer is - tan x
  23. S

    I just read somwhere thatif cos a = cos dthen a=2n(pi)±d where

    i just read somwhere that if cos a = cos d then a=2n(pi)±d where n is integer So, if cos (b*ln (i/j))= cos (-b (lni/j))=cos(b*ln(j/i)) can i write b*ln i/j = 2n(pi)±b*ln(j/i) or bln(j/i)+bln(i/j)=2n(pi) or 2n(pi)=0 b=n(pi)/(ln(i/j)-ln(j/i))=n(pi)/(b*ln(i/j)) then replace b in...
  24. R

    Help with 1 step in proof of d/dx sin x = cos x

    I understand everything in the proof except the last step I have written here. What comes after, I understand. How is it that the cosine and sine are able to be factored out of the fraction? That one step gets me. I was never too good with my trig, and have finally gotten a decent grasp of...
  25. J

    How to find the exact value of cos 67.5 ?

    One of the questions in the homework for online precalc class I'm taking is to find the exact value for cos (67.5). At first I didn't realize that I should just take the half angle of 135, so instead I tried to find the value for cos (45 + 45/2), and got stuck at this point. If I...
  26. P

    Cos & Sin: Learn How to Work With Them

    Yes, I have searched on google/youtube but I want to know how to work with them in tasks for example ramp friction ##f=mgcos0##
  27. L

    Reduction formulas for integral of sin and cos

    Integrate sin2(x)cos4(x)dx using reduction formulas? My book says integral sin2(x)cos4(x)dx= integral cos4(x)-integral cos6x dx Now the reduction formula for n=6 for integral cos6(x)dx= (1/6)cos5(x)sinx+(5/6) integral cos4(x)dx Here is the part I don't get: It then says ...
  28. A

    Solving SIN, COS, TAN with a TI-30XA Calculator

    Hello, I'm having some problems. So for geometry class today, the teacher taught us this COS, SIN, TAN stuff. I got the concept how to get the fractions from the triangle and everything. Problem is how to plug it in the calculator. I have a basic TI-30XA, and I'm trying to plug in fractions...
  29. Z

    Question about uncertainties after applying cos

    Homework Statement I have conducted a simple experiment about polarized light. The angles were 0, 10, 20, 30 etc. The device used to measure the angles has units of 1 degree. Therefore the uncertainty is +-0.5 for each angle measurement. I was then required to produce a column beside this...
  30. R

    Solving 10.0km + 5.0km [E15S] with Cos and Sin Laws

    Homework Statement 10.0km [N] + 5.0km [E15S] Homework Equations Cosine Law The Attempt at a Solution If you draw it out you see that 10km is 90 degrees north. From the 10km end, you do E15S for 5km. Therefore, a = 10km, b = 5km, c = ?, C = 90 - 15 = 75. Therefore: c^2...
  31. J

    Area Between Two Curves (Sin and Cos)

    Homework Statement Sketch the regions enclosed by the given curves. And determine the area between the curves. y = 7 cos 3x, y = 7 sin 6x, x = 0, x = π/6 Homework Equations The Attempt at a Solution Okay so i ended up solving the question, because i used the help of my graphing calculator...
  32. S

    Expansion of cos 15 x interms of cos

    I have expanded cos 15x interms of cos. I hope some one who needs it can use it. I have verified this formulae using symbolic matlab: so its geniune cos 15*theta = 16384*cos(theta)^15 - 61440*cos(theta)^13 + 92160*cos(theta)^11 - 70400*cos(theta)^9 + 28800*cos(theta)^7 - 6048*cos(theta)^5 +...
  33. D

    Integration by substitution of sqrt cos theta.sin cube theta

    Homework Statement To show that \int_{0}^ \frac{\pi}{2}\sqrt{cos\theta}sin^3(\theta) d\theta = 8/21 The Attempt at a Solution The above expression was simplified as \int_{0}^ \frac{\pi}{2}\sqrt{cos\theta}sin^2(\theta) sin(\theta) d\theta \int_{0}^...
  34. B

    Integral (sin x/2 - cos x/2)^2

    Homework Statement I'm unable to solve this integral. I get a result, but it doesn't match the solution. \int(sin \frac{x}{2} - cos \frac{x}{2})^2 \mathrm{dx} \int(sin \frac{x}{2} - cos \frac{x}{2})^2 \mathrm{dx} The Attempt at a Solution (attachment?) I'd be grateful for highligting my errors.
  35. T

    Position in Motion: When to Use Cos & Sin in x=A*sin(wt+phi) or x=A*cos(wt+phi)?

    In what kind of cases do u we formulate the equation type x=Asin(wt+phi) or x=Acos(wt+phi)...and if for example we use it to define the position of some thing in motion when do we know when to use cos and when to use sin...?
  36. Z

    Eqn for SHM, sin function, so why cos?

    I had thought the eqn of simple harmonic motion is a sinusoidal function of time, with the eqn being: x(t) = A sin(wt + ∅0) Halfway down this page: http://electron9.phys.utk.edu/phys135d/modules/m9/oscillations.htm in Problems: in solution (a) it gives; The displacement as a...
  37. L

    I insert in my calculator cos 50x60 = 42.42

    1) cos 60o = vx0 / 50 => vx0 = 50.cos 60o = ? 2) sin 60o = vy0 / 50 => vy0 = 50.sin 60o = ? OK so I use my calculator for 1) and I insert in my calculator cos 50x60 = 42.42 but this is not the right answer because the answer is 25 m/s because the answers...
  38. G

    Working at proof derivative cos

    I have tried to formulate proof for derivative of cosine and this is what I ended up with: Does anyone see any errors? And since I found this proof a bit long, does anyone know any shorter version which proves all the steps involved? Step1 http://www.viewdocsonline.com/document/4bp3pb Step2...
  39. B

    Complex Analysis Integration with Sin and Cos

    Homework Statement Compute the integral from 0 to 2∏ of: sin(i*ln(2e^(iθ)))*ie^(iθ)/(8e^(3iθ)-1) dθ (Sorry for the mess, I don't know how to use latex) Homework Equations dθ=dz/iz sinθ = (z - z^(-1))/2i The Attempt at a Solution So I tried to change it into a contour integral of a...
  40. E

    Partial differentiation of cos (in vector calculus)

    Homework Statement So using standard spherical polar co-ordinates, my notes define a sphere as r(s,t) = aCos(s)Sin(t) i + aSin(s)Sin(t) j + aCos(t) k and the normal to the surface is given by the cross product of the two partial differentials: \partialr/\partials X \partialr/dt...
  41. AcousticBruce

    Px = P cos θx equation question.

    P_x = P cos θ_x is Px always the adjacent line of the triangle?
  42. L

    Position of a particle is given by x = (2 cm) cos 10πt

    Homework Statement The position of a particle is given by x = (2 cm) cos 10πt, where t is in seconds. (a) What is the frequency? Hz (b) What is the period? s (c) What is the amplitude of the particle's motion? cm (d) What is the first time after t = 0 that the particle is at its...
  43. O

    How to get θ sin and cos are together in 1 equation

    b2cos2θ+2cosθ(-mb+bc2-bz-bcsinθ)+2sinθ(cm-cz)-c2sin2θ=p How to get θ in terms of b,c,m,z,p The equation i formed to calculate the dynamic PLs, anyone can help to solve this, i would much appreciate! I am doing my FYP!
  44. C

    Is There a Trick to Integrating with Law of Cos?

    I hope I am posting this in the correct area. This is not specificly a homework question, but something that keeps stumping me on numerous Electrostatic problems. When attempting to Intigrate for finding the electric field or potential, I frequently end up with an integral over the form ∫∫∫...
  45. V

    Theta in converting sec to cos

    Homework Statement I saw in my calculus book that something along the lines of arcsec \frac{4}{\sqrt{pi}} = x was converted to arccos \frac{\sqrt{pi}}{4} = x. I understand that sec and cos are reciprocals, but I don't see why has to be flipped as well. Homework Equations cos (θ), sec (θ)...
  46. X

    How to define acos in relation to cos?

    Hey, Does anyone know how to calculate the formula for acos in relation to cos? We know that cos (∏/3) = 0.5 and acos(0.5) = ∏/3 However, I assumed I could calculate acos(x) in relation to cos(x) as: 1/cos(x). Well, I assumed wrong :( Is there any way to do this? Thanks
  47. J

    How to prove that sin square x cos square x is identical

    Homework Statement 1) how to prove that sin square x cos square x is identical to 1/8 (1- cos 4x)? 2) f(x) = x square +7x -6 ----------------, show that when x is sufficiently small for (x-1)(x-2)(x+1) x^4 and higher powers to be neglected. Homework Equations 1) cos (s +...
  48. nukeman

    Tangential and Radial acceleration - Sin and Cos simple question

    Homework Statement Im confused about something. Ill post the answer sheet to a question. It has all the data you need. BELOW: NOW... for Tangential component of the acceleration, WHY did they pick cos? and for Radial, WHY did they pick sin? I am starting to do a lot of FBD to equations...
  49. P

    Find the Value os Cos Vectors

    The points P, Q and R have position vectors 2i + 5j -3k, i + 4j - 2k and 3i + 3j - 2k, respectively. Given that the angle between PQ and PR is theta, find the value of cos of theta: So, the first thing I did was to find PQ and PR. I got: PQ = -i -j + k PR = i + 2j + k Then what I did...
  50. A

    Partial Derivate of multivariable cos

    Homework Statement Partial derivative of R = vt cos x with respect to t Homework Equations NA The Attempt at a Solution Keeping the other variables constant, I get 'v cos x'. (t is 1) I just want to check this, because it's part of a larger problem and I feel my answer is way...
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