Circle Definition and 1000 Threads

This isn't really a HW question, it's just something that's been confusing me in my Calc class. We recently went over how to find curvatures of curves in 3D space. In lecture, the professor went over a simple example: a circle of radius 3 at any given point. Maybe it's because I don't...

I got a problem that I need to figure out. I have a piece of pipe 20 inches long and I bend it on a radius at 90 degrees. I measure from the back of the pipe to the end of one side and get 9, I flip it the other way and do the same thing and get 13.555. If you add those you end up with a...

Actually I changed my mind and feel like it should be ((pi*r)(2*pi*r)) by my faulty thinking. Since pi*r would give you a line wrapped halfway around a sphere, I was thinking you could repeat this line in a radial pattern around the outside of a sphere (2*pi*r) times to get the surface area...

Given 2 points on a circle, call them A and B. I know the cartesian coordinates of A. I also know the radius of the circle, the slope of the tangent line at A, and the length and direction of the arc between A and B. I don't know the coordiates of the center of the circle. How do I find...

Homework Statement What is the approximate uncertainty in the area of a circle of radius 5.3 * 104 cm? Express your answer using one significant figure. Homework Equations A = pi*r2 The Attempt at a Solution Using the given radius, I found the area to be 8.8 * 109 cm2. And since...

Hi, All: I saw an argument in another site re the claim that the genus-g surface Sg does not retract to a circle. The argument was that,using/assuming H_1(Sg,Z)=Z^{2g}; and H_1(C,Z)=Z ; Z the integers and H_1(Sg,Z) if there was a retraction r: Sg-->C , then , for i being the inclusion ...

Homework Statement A piece of wire 40 cm long is cut into two pieces. One piece is bent into the shape of a square and the other is bent into the shape of a circle. How should the wire be cut so that the total area enclosed is a (a) maximum and (b) minimum? Homework Equations Area...

I have been toying with a java programming project for a few months now. I want to depict a satelite orbiting a planet (2 dimensional). I've scaled down certain constants to fit the screen and have put GM (mu) at 200000 and the distance from the gravitaional body, a planet, at 200...

Hi, my first post here is a simple one (hopefully) and is a from a series of mechanical comprehension questions I had been given. I have no idea which one is correct. If you do know the answer would you be able to give a brief explanation to why it is? Also, if anyone has any mechanical...

Hi guys! I learned yesterday what an osculating circle is and I am learning how to find the radius of curvature of some curves. For example I have found that for y=x^2 the radius of the osculating circle for the point [0,0] is 0.5 (That's why circular mirror works similarly to parabolic mirror...

I'm writing a little program for generating some images, and at one point I need to calculate how much of a circle is on either side of a straight line that bisects the circle. The line is always vertical so it is easy to get the value of how much of a horizontal line segment within the circle...

Homework Statement Let z1; z2; z3; z4 be four complex numbers on the unit circle (i.e., |z1|=|z2|=|z3|=|z4|=1). It is known that z1+z2+z3+z4=1+i . Find the value of 1/z1 + 1/z2 + 1/z3 + 1/z4 Homework Equations 1/z = barZ/|z|^2 The Attempt at a Solution I've been trying for about a day now...

Homework Statement Evaluate f(x,y)=y2\sqrt{1-x2} over the region x2+y2< 1 Homework Equations The Attempt at a Solution using x limits between -1 & 1 followed by the y limits of 0 & \sqrt{1-x2} \int\inty2\sqrt{1-x2}.dy.dx Evaluating this and multiplying be 2 to get the...

My friend was telling me about something he read about involving points on a circle that seemed kind of cool. It went something like this: Have a circle of radius 1, and mark n equally spaced points on the outer perimeter. Choose one of the points, and connect all other points to it...

Area in cardioid and outside circle -- Using Double Integral Homework Statement Find the area inside of the cardioid given by r = 1 + cos\theta and outside of the circle given by r = 3cos\theta. Homework Equations \int\intf(x,y)dA = \int\intf(r,\theta)rdrd\theta not really relevant...

So I came across http://amasci.com/miscon/eleca.html#circle" on W Beaty's site and it's not sitting well with me. Here is a quote: This doesn't seem right to me. My impression has always been that the charges flow from one of the slots (hot) in the wall socket and return on the other...

Homework Statement A large circle is inscribed with 3 smaller circles, eachhttps://www.physicsforums.com/newthread.php?do=newthread&f=156 of the four circles is tangent to the other three. If the radius of each of the smaller circles is a, find the area of the largest circle. Homework...

Homework Statement "Set up an integral involving a function and evaluate the integral to prove the formula for the area of a circle of radius r is pi*r^2. Show all steps." 2. The attempt at a solution I imagined the circle as an infinite tiny arc lengths or "circumference's", with each arc...

Homework Statement Find a differential equation whose solution is a family of straight lines that are tangents to the circle x^2+y^2=a^2 where a is a constant. The Attempt at a Solution So actually I'm stuck on the first part, coming up with such an equation. After some work I came up with...

So I ran across this problem on the 'net and I can't determine "x". The arc length of the circle is 360. I added some other variable and took what I know about a circle and intersecting lines. I wound up with four variables and four equations. x = 1/2 (y + 67) w = 1/2 (z + 147) y +...

Homework Statement The average speed of an orbiting space shuttle is 19800 mi/h. The shuttle is orbiting about 233 mi above the Earth’s surface. Assume the Earth’s radius is 3963 mi. How long does it take to circle the earth? Answer in units of h. Homework Equations I think it...

Find the moment of inertia of a wire, AB, of mass M and length pi*a, which is bent into a semicircle, about AB. Mr^2/b] [b]The mass of the wire is M=pi*a*m, where m is the mass per unit length of the rod. Then a small element, ds is regarded, of the circumference of the semicircle as being...

The pendulum bob in the above figure must circle the rod interrupting its swing, and the string must remain taut at the top of the swing. How far up must the bob be raised before releasing it to accomplish these goals? I don't know where to begin with this because I don't quite understand...

Does a circle have a constant rate of change of it self that defines it as a circle. I have never heard of such a thing but I am curious. It must right?? Since every circle is the same no matter the radius(the arch will change by some constant amount per radian) If that doesn't make...

Homework Statement I'm trying to figure out the radius of a circle that intersects two points on a right triangle. One side of the triangle is tangent to the circle and the other intersects it. I have attached an image that helps further explain what I'm talking about. Knowing what I have...

I'm trying to figure out the radius of a circle that intersects two points on a right triangle. One side of the triangle is tangent to the circle and the other intersects it. I have attached an image that helps further explain what I'm talking about. Knowing what I have listed in the image is...

Can say me why annulus and circle are not homeomorphic?

I am learning about the unit circle and I am a bit confused. So, I have my circle drawn with radius 1 and I sketched a right angled triangle inside it so that the hypothenuse has a length of 1. I think what is making me confused is the meaning of sine, cosine and tangent. They are...

Homework Statement http://img40.imageshack.us/img40/7174/thecircleu.jpg A circle whose equation is http://img830.imageshack.us/img830/5443/thecircle2.jpg is tangent to the y-axis at point A(0,3) [see graph]. "a" is a parameter. Find the value of a. The Attempt at a...

Hello! Hope someone can help me, I already tried some solutions, but couldn't come to a final conclusion. I need to create a circular area, from which particles are emitted. For this, I have a frequency distribution of x and y. I have around 100 points, but to simplify matters I list only...

Homework Statement Given the circle (x+1)^2 + (y-3)^2 = 25, determine the equations of the tangents to the circle with the slope -3/4.Homework Equations y = mx + bThe Attempt at a Solution I thought that if I could find the equation of the line that passed through the center of the circle and...

Homework Statement There is a semicircle submerged in the water. The distance between the surface and the top of the semicircle is 2 ft, and the radius is 5 ft. Find the hydrostatic force. The answer is 1.2 * 10^4 N. Homework Equations y = sqrt(25 - x2) The Attempt at a Solution...

Homework Statement Ok hey guys this is my first post so be nice ;). I just wanted to know how to see if a line only intersects the circle once (ie a tangent) I know about double intersections with the quadratic and no intersection with a negative surd in the quadratic equation but is there a...

Homework Statement Find the Linear Fractional Transformation that maps the line Re\left(z\right) = \frac{1}{2} to the circle |w-4i| = 4. Homework Equations For a transform L\left(z\right), T\left(z\right)=\frac{z-z_{1}}{z-z_{3}}\frac{z_{2}-z_{3}}{z_{2}-z_{1}}...

We've always been using mm^4, but I see in my answer book (answer written below) that one solution says R^4. Is it the same thing, just that R^4 is used for a circle? The measurement in my exercise are in mm. I did get the answer, I just wasn't aware I was supposed to write it in terms of R^4.

Homework Statement Equation of a circle is: x^2+(y+a)^2=R^2 x intercepts are +/-\sqrt{3} and arclength above x-axis is \frac{4\pi}{3} Find a and R.

I'm looking for a formula that subtracts the area of an inscribed circle of a shape from the circumscribed area of the shape. I've confused myself on this one and can't seem to figure it out. The shape is a regular polygon (all sides and angles are equal). What should be given to "plug in" is...

Hi, I'm a mechanical engineer that's new to optics. I'm trying to determine the best location to place an image sensor for an optical system with multiple lenses and mirrors. In doing so, I've come to the understanding that the best position to put the sensor is at the circle of least...

Homework Statement An object is moving counterclockwise in a circle of radius r at constant speed v. The center of the cir- cle is at the origin of rectangular coordinates (x, y), and at t = 0 the particle is at (r, 0). If the “angular frequency” is given by ω = v/r, show that...

Homework Statement I previously calculated the electric field for the the arc of the circle and got Ex= Q/2pi^2 e_0 a^2 sin(theta) Ey= Q/2pi^2 e_0 a^2 (1-cos(theta)) I need the electric potential Homework Equations The Attempt at a Solution V=Edr i got an answer interms of theta and since I...

Hello guys! Lets say we have a laser beam and we send it to a michelson interferometer. Why the beam pattern at the screen gives circles and not lines or something else? Thanks P.S. see for instance http://techtv.mit.edu/collections/physicsdemos/videos/9823-michelson-interferometer

Double Integral bounded by Circle? Double integral of (2x-y)dA bounded by circle of radius 2, centered at origin I just need to figure out the limits for my integrals... I am basically lost, can someone show me how to break this up. I tried doing what I did with the previous triangle bound...

I have the proof for pi r^2 (sorry a bit rusty on latex at the moment) Y'all might want to take a try at it. I'll post the proof in a couple of days thanks vector22

Hello everyone! I'm trying to find out how to precisely construct three congruent circles inside a larger circle, each tangential to both the outer circle and the other two circles. For example: http://img4.imageshack.us/img4/1044/verybasicdrawing.png An image I found on the internet...

Homework Statement [PLAIN]http://img101.imageshack.us/img101/2786/21417885.png [96] Homework Equations The Attempt at a Solution E= kdq/r^2 dq=Q/(pi a) dx Ex = 0 , Ey= E sintheta sin theta = sqrt(a^2 - x^2)/a by Pythagorean theorem Ey = kQ/(pi a* a^3) integral from -a to a sqrt(a^2 - x^2)dx...

Hi all, Let me state up front that I'm a math idiot. I minored in it in college 20+ years ago and haven't needed it as a software engineer...until now. I'm trying to solve a problem for work that's got me pulling my hair out, mostly because I'm having to relearn so much math I'd forgotten...

Hi, I am using the hough transform to perform circle detection. I am able to perform a hough transform and plot the results, but how exactly do I now take my hough transform to actually get meaningful information. I know the size of the my circle (it's radius), but what information am I looking...

Not a homework question, I was just hoping someone could assist me with understanding some math. Actually, more accurately, I was wondering if someone could double check the math on the following website. http://www.otherpower.com/statormold.shtml If you scroll down you will see some...

Hi, Math forums! I need some help with a circle question. 3x^2 + 12x + 3y^2 - 5y = 2 And I was supposed to find the radius and center of the circle, So I first divided by 3: x^2 +4x + y^2 - 5/3y = 2/3 And then I complete the square x^2 + 4x + 4 + y^2 - 5/3y + 25/36 = 2/3 + 12/3 +...

Homework Statement An airplane is flying in a horizontal circle at a speed of 410 km/h (Fig. 6-41). If its wings are tilted at angle a = 42° to the horizontal, what is the radius of the circle in which the plane is flying? Assume that the required force is provided entirely by an...