Tagged Questions
0
votes
1answer
11 views
Ray Disk intersection
So if I have a ray parameterized as $O + tD$ where $O$ is the origin, $D$ is the direction and $t$ is the parameter variable and a flat circular disk with a center point $P$ in 3D space and a radius ...
2
votes
4answers
40 views
Relation between chords length and radius of circle
Two chords of a circle, of lengths $2a$ and $2b$ are mutually perpendicular. If the distance of the point at which the chords intersect,from the centre of the circle is $c$($c<$radius of the ...
1
vote
1answer
30 views
Are the area of a circle inscribed in a square and the area of the “spandrels” (the four corners that remain) commensurable?
And how would you demonstrate that most simply?
See the beginning of my blog post for a little more:
http://seekecho.blogspot.fr/2013/02/different-ilks.html
2
votes
3answers
66 views
Geometry - Equilateral triangle covered with five circles
I have to cover an equilateral triangle (whose sides are 1m long) with 5 identical circles: what's the minimum radius of the circles?
0
votes
1answer
62 views
How to find a point on the tangent line whos length is 1?
im trying to figure out a formula to find the point(x,y) on a tangent line whos length is between 0 and 1 while it rotates around the unit circle uniformly, so the point would either be right on the ...
2
votes
1answer
50 views
Center of circle that has two points on its circumference and a known tangent
I've found a related question, which helped me get started on this. I can get it to work for the example on the question, but I'm running into an issue when the tangent is not y = 0.
Other question ...
1
vote
1answer
17 views
2D triangulation
I understood what it is from the following link:
http://electronics.howstuffworks.com/gadgets/travel/gps1.htm
But I want to know :
In a 2D plane, if we know the (x, y) positions of three “guard” ...
1
vote
1answer
50 views
Two sticks between two concentric circles
Let's start with two concentric circles of radii $r<R$. Then we put two sticks inside the outer circle while avoiding the inner circle, say $AB$ and $CD$.
Then we compare the length of inner ...
0
votes
2answers
117 views
Calculating circle radius from two points and arc length
For a simulation I want to convert between different kind of set point profiles with one being set points based on steering angles and one being based on circle radius.
I have 2 way points the ...
1
vote
1answer
35 views
Similarity of triangles in a circle
The problem:
c is a circle with a diameter AB. t is the tangent at the point B. Now C and D are two points on t and at different sides of B. I draw the line segments AC and AD, the point where AC ...
0
votes
2answers
55 views
Circle problem. Finding the length of a segment in the circle.
Here is a picture of the problem. Note that $M$ is the midpoint of $OB$. How do I figure out what $MH$ is?
Original image here
2
votes
1answer
44 views
One circle, two lines Apollonius' problem
I've been trying to solve special case of Apollonius' problem, where instead of 3 circles i have 1 circle and 2 lines. Acording to:
...
2
votes
1answer
36 views
Point on circumference a given distance from another point
I am writing a game and need to figure out some math. If I have a circle with the equation $r^2 = (x-d)^2+(y-e)^2$, where $r$, $d$, and $e$ are constants, and a point $A(a,b)$, how do I find the ...
1
vote
1answer
59 views
Calculating mean velocity of an orbiting body as it moves towards a point.
I'm making a game, in the game planets orbit a central point in circular orbits, they move directly towards their targets and the vector is simply added to their orbital path. Whilst not realistic it ...
1
vote
2answers
32 views
How to calculate angles required to lay out flat pieces in a circle
I want to construct a wheel made of flat pieces of wood, something like this picture:
I am unsure how to calculate the difference in angle between each of the flat pieces of wood that make up the ...
0
votes
1answer
33 views
How to determine if two points lie in a particular section of circle.
I'll take assistance from the figure below.
O is the center of the circle, and A,B,C are the points on the circle, and are known. i.e. the x,y coordinates of these three points are known. I want to ...
2
votes
1answer
107 views
How do we know $\pi$ is a constant? [duplicate]
How did the ancient Greeks discover that the ratio of a circle's circumference to its diameter is constant? It does not seem so intuitive. Thanks!
1
vote
2answers
37 views
Diameter of a circle with 3 coordinates
The question is: A circle has the points $A=(6,-1)$ $B=(10,-3)$ and $C=(-2,-9)$ on its circumference. A diameter of the circle is drawn which is parallel to BC. How far apart are the two parallel ...
1
vote
1answer
98 views
Math - 11th Grade Geometry - Locus
I have a test tomorrow and this might be a question on it. I do not know the answer and I have no idea how I would draw it out if I had to. The question is...
Describe the locus of the centers of all ...
3
votes
2answers
85 views
Euclidean Geometry Area Problem
Let $\Gamma $ be the circumcircle of triangle $ABC$. Let $A_0$ be the center of the circle lying outside of $\triangle ABC$ and which is tangent to the segment $BC$ and to rays $\overrightarrow{AB}$ ...
1
vote
1answer
47 views
Form a Circle with Circles
I need to form a perfect circle out of circles.
Given N number of circles each with radius R, how can I find the distance away from the center?
0
votes
2answers
50 views
Prove that the two line<->circle intersecting points multiplied by eachother are equal to the square of the circle's tangent
On my current math assignment there is a question as follows:
Prove the following:
A line $k$ through point $P$ intersects the circle with middle $M$ in the points $A$ and $B$. Another line $l$ also ...
2
votes
1answer
51 views
Maximum number of points a minimum distance apart in a semicircle of certain radius
You have a circle of certain radius $r$.
I want to put a number of points in either of the semicircles. However,
no two point can be closer than $r$.
The points can be put anywhere inside the ...
0
votes
3answers
109 views
Intersection of chord with circle knowing the length and a point
Let's take a circle with radius R, and center in O (0, 0). We take on this circle a point A with coordinates xA and yA.
We know that point A is one of the endings of a chord with length l.
Which is ...
0
votes
2answers
41 views
water flow through circular pipe
Water flows through a circular pipe of internal diameter of 3cm at a speed of 10cm/s
if the pipe is full how much water flows through the pipe in one minute.
1
vote
0answers
118 views
Finding side and angle of isosceles triangle inside two circles
I'm having a problem that I'm not sure how to solve (or if it's even possible). It's not homework, just something i'm struggling with for a project. :)
Basically, there are two circles, represented ...
2
votes
1answer
48 views
Finding the incircle of a circle sector
I'm not great at mathematics so I'm sure this is trivial to most. I have been searching around however and not been able to find how to figure out the incircle of a circle sector, or, in other words, ...
1
vote
1answer
38 views
Radius of an arch given length and Area of sector
the lengh of an arc of a circle is 12cm.the corresponding sector area is 108cm^2
Find the radius of the circle.
3
votes
2answers
49 views
Apollonius circle
I'm given two points, $A$ and $B$, and two lengths, $b$ and $c$. I need to find the locus of point $C$ such that $BC:AC=b:c$.
This link describes Apollonius circle of first type, but I can't seem to ...
0
votes
3answers
71 views
How many circles fit in the same two dimensional orbit?
I'm trying to figure out how many circles/planets can fit in the same two dimensional orbit. All of the planets and orbits are perfect circles but the planets size and amount can vary.
This is for ...
0
votes
3answers
36 views
Why exactly is π(mean of radius)² less than the mean of the areas calculated for each radius?
For example, a uniformly distributed value for a radius between 0 and 1 is calculated many times and the area for each radius is calculated:
...
2
votes
4answers
108 views
Circle/Triangle math problem
The question asks to find angles $\angle X$ and $\angle Y$, however I don't know how to do this without assuming that lines $\overline {GO}$ and $\overline{OJ}$ are parallel. The only angle given is ...
12
votes
2answers
183 views
6 point lying on a common circle
$Z$ is an interior point of segment $XY$. Three semicircles are drawn over segments $XY$, $XZ$ and $ZY$ on the same side. The midpoints of the arcs are $M1$, $M2$ and $M3$ respectively. A circle ...
2
votes
1answer
146 views
How to find the central angle of a circle?
My book states the following:
Likewise, we can take a circular cone with base radius $r$ and slant height $l$, cut it along the dashed line in Figure 2:
and flatten it to form a sector ...
0
votes
1answer
57 views
Formula to calculate a position given three 2D locations and distance
I am doing a project for my final year computer science and normally post on stack-overflow but this question seems more suited for here. I need a formula to calculate my position from three 2D points ...
1
vote
1answer
85 views
Find parametric expression of an arc given its start point, end point and central angle in 3D cartesian coordinate system
In a 3D cartesian coordinate system, the coordinates of start point and end point have been given as $(x_1, y_1, z_1)$ and $(x_2, y_2, z_2)$. If the central angle of the two points (the one smaller ...
1
vote
2answers
44 views
Geometry: Arcs of a Circle
I think this is solved using the Pythagorean theorem but cant figure out how to get the length of PQ. Any help?
0
votes
1answer
55 views
Positioning Circles in a Ring
I am working on a program and need to be able to draw circles around the ring. The circle currently in the ring is manually placed. Is there an equation for drawing non overlapping circles inside a ...
2
votes
2answers
111 views
How do I find the area of a circle inside a square?
In the figure above, the circle with center $O$ is inscribed in square $ABCD$. What is the area of the shaded portion of the circle?
(A) $\pi/4$
(B) $\pi/2$
(C) $\pi$
(D) $3\pi/2$
(E) $2\pi$
0
votes
1answer
67 views
Space filling problem with equal radii on earth
I have two circles. Both origin at San francisco $(37.77493,-122.419415)$, The larger circle has Radius $R_1$, the smaller circle has radius of $R_2$.
What's the fewest number of additional ...
1
vote
5answers
100 views
Arcs of a circle Geometry and angles
How do I find out what the radius length of the angle is? The answer is D by the way.
1
vote
2answers
37 views
How can i find the lenght of a side of a polygon with known number of sides that has a circle with known diameter inscribed in it?
How can i find the lenght of a side of a polygon with known number of sides that has a circle with known diameter inscribed in it? I'm a web-developer intereseted in this certain problem, that would ...
0
votes
3answers
119 views
Find the length of this chord.
I've been trying to solve this geometry question for past 2 hours but haven't got the answer yet.
There are two concentric circles or radius $8 cm $ and $13 cm$ with the common center $O$. $PQ$ is ...
1
vote
2answers
77 views
How do I calculate a point on each of three circles that have specific distance to each other?
I am trying to write code for a computer simulator. I need to simulate a complex mechanism where each link has a known length and the ends of the links are connected to a triangle. I would like help ...
-4
votes
1answer
173 views
Geometric Definitions: What is a straight line? What is a circle?
What is a straight line? I need a geometric definition of it. The equation of a straight line is known to me.I am saying about a straight line of 2D plane.
What is a circle? I need a geometric ...
2
votes
1answer
449 views
Calculating circle radius from two points on circumference (for game movement)
I'm designing a game where objects have to move along a series of waypoints. The object has a speed and a maximum turn rate. When moving between points p1 and p2 it will move in a circular curve ...
10
votes
8answers
792 views
Finding circumference without using $\pi$
If the area of a circle is $254.34\ldots\text{ cm}^2$ it has a diameter of $18\text{ cm}$, is it possible to find the circumference without using or making the irrational constant Pi ...
0
votes
2answers
76 views
Finding the locus of a point
I was thinking about the above problem .Can someone point me in the right direction? Thanks in advance for your time.
3
votes
1answer
70 views
Ноw many equal circles can be placed around a circle?
How many circles of radius $r$ can be placed around a circle of radius $R$ (close to it)? $r$ can be bigger, equal or smaller than $R$.
3
votes
1answer
119 views
Finding a circle that touch two other circles and a line
Given two circles $(x1, y1, r1), (x2, y2, r2)$ and a line passing through two points $A(xa, ya)$ and $B(xb, yb)$. How to find a circle $(x3, y3, r3)$ that is tangent to line and two given circles?
I ...
