Tagged Questions
2
votes
3answers
13 views
Right-angled isosceles triangles
If a right-angled triangle is isosceles then the other two angles must be equal to $45^\circ$ ?
Is this always the case or are there other possible right-angled isosceles triangles?
0
votes
0answers
15 views
Find next point in ellipse given the chord length
I would like to draw a cloud programmatically. For this reason I need to know where to draw the next circle around the ellipse.
Given the chord (circle radius), how can I calculate the next point in ...
1
vote
1answer
32 views
Find the value of $\tan^2\alpha+\cot^2\beta$
A circle with centre o have two chords AC and BD,which are intersecting each other at P.If $\angle AOB=15^\circ$ and $\angle APB=30^\circ$,then find out value of
$$\tan^2\angle APB+\cot^2\angle COD$$
...
0
votes
1answer
47 views
Drawing an arc between two points
I was writing a java program to draw an arc.
Arc2D.Double(int x,int y,int width,int height,int startAngle,int arcAngle,int type);
Since, I'm not familiar with the mathematics behind drawing arc, I'm ...
0
votes
1answer
61 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 ...
0
votes
3answers
60 views
Distance between two antennas
I am trying to find out the formula to calculate how high antennas need to be for Line of Sight (LoS) propagation.
I found:
d = 3.57sqrt(h)
also
...
0
votes
2answers
43 views
Calculate new positon of rectangle corners based on angle.
I am trying to make a re-sizable touch view with rotation in android. I re-size rectangle successfully. You can find code here
It has 4 corners. You can re-size that rectangle by dragging one of ...
0
votes
3answers
40 views
Please help me find a formula to find the 3rd point in a right triangle
I'm trying to figure out how to plot a 3rd point on a graph
Given the following line segments and angles
Is there a formula for the 3rd point?
Note: This image is just for an example. The base ...
1
vote
1answer
27 views
Please help me to find an equation to find the 3rd point in an arc.
Long story short, I want to animate the rotation of an object that's based off a circle.
Given the center point of the circle, the radius, and one of the points in the arc, is it possible to find the ...
0
votes
0answers
20 views
How can I align the angle between points with the magnetic heading as the points move?
I have 3 robots which must track a point. The distance between all the robots and the point is known so a triangle can be formed between any 2 robots and the point.
If I find the angles in the ...
4
votes
1answer
38 views
Optimal rotation to align a circle with external points
I have a circle $C$ with radius $r$ and a set of finite points $P=\left \{ p_1,p_2,\ldots,p_n \right \}$ are identified external to the circle $C$. These points may lie on the exterior or the interior ...
1
vote
1answer
60 views
finding Length of a diagonal
Given Quadrilateral ABCD in such that $AB<BC<CD$ creating increasing arithmetic progression with sum of $27$ cm.
$\measuredangle BCD=60^{0}$. the diagonal $BD=\sqrt{133}$ cm, and it divided ...
0
votes
2answers
116 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 ...
0
votes
1answer
18 views
What is Angle(A,b) about something.
I was reading a paper and came through a notation saying ....
Angle = Angle(A,B) about C.
Can anybody tell me what exactly it means.
Thnaks,
Harsha
0
votes
1answer
21 views
Need “up” vector to calculate distance from a focal plane given world coordinates (SOLVED)
I have a RGB image, and for each pixel in the image I also have its real world coordinate. I also have the location (real world coordinate) yaw, pitch and roll of the camera. I am trying to produce ...
4
votes
0answers
43 views
How to find the maximum diagonal length inside a dodecahedron
I am trying to find the maximum length of a diagonal inside a dodecahedron with a side length of 2.319914107*10^89 meters. I am not sure if any other information than that is needed, if it is I ...
0
votes
1answer
56 views
Euclidean triangle. Does this one exist
Does $\exists$ a Euclidean triangle $ABC$ with $\sin(A) : \sin(B) : \sin(C) = \frac{1}{4} : \frac{1}{3} : \frac{1}{2}$?
3
votes
1answer
26 views
Largest Quadrilateral from a Set of Points
I posted the below on StackOverflow but was directed here as this may be more mathematical problem but I was looking to implement an algorithm....
I have a discrete set of points.
From this set of ...
0
votes
0answers
12 views
Is there a formula to get the changes in ship course from wind and current?
Anyone know how to get the changes of degree's in ship course that affected by wind and current?
I thinks it maybe related with the speed and degree of WIND and CURRENT. But I don't know how to ...
4
votes
1answer
62 views
How can I calculate the angle of a slice of an ellipse?
I'm attempting to draw a pie-chart programmatically, using an ellipse instead of a circle, but I'm having trouble calculating the correct angles for the slices. If it were a circle, I could use the ...
0
votes
1answer
17 views
Coordinates of all 'N' points, equidistant from each other , on a circle of radius 'R' whose center is (h,v) from the origin?
How would I calculate the coordinates of all 'n points' equidistant from each other on a circle of radius r and the center coordinates of (h,v) from the origin .
0
votes
1answer
40 views
How to find a new point on rectangle based on an known point on the same?
I have rotated a rectangle a certain amount of degree and got the point(x,y)=(130,40) which was previously (152,60). Now i want to find the x,y(marked as red) value at another location based on the ...
0
votes
0answers
34 views
Geometry question
The sides of a triangle are given to be $x^2+x+1$ , $2x+1$ and $x^2-1$. Then the largest of the three angles of the triangle is
a)75 degree
b)$\dfrac{x}{x+\pi}$
c)120 degree
d)135 degree
please ...
3
votes
1answer
98 views
How to simplify this trigonometric expression?
I was trying to solve a problem taken from an Physics Olympiad when I came across a curious and complex mathematical expression. I can not prove with what I know so far about mathematics, does could ...
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
1answer
34 views
Trig problem, finding angles and ranges
I have what may well be a simple problem, but it's been too long since I've done this type of problem. From a fixed point (intersection of all the lines), the angles to 3 other fixed points $a,b,c$ ...
1
vote
2answers
49 views
How do I find the surface area of an angled conic base?
Thank you for viewing my question.
I need help creating a formula for finding the surface area of a conic base. (eg. I install a flood light on my roof, I want to know how much surface area it will ...
3
votes
3answers
113 views
How can I find the points of intersection between the curves $r=1+\sin\theta$ and $r=1-\sin\theta$?
Find the points of intersection for the curve $r=a(1+\sin\theta)$ and $r=a(1-\sin\theta)$
My book says the answer is $(0,0),(a,0),(a,\pi)$.
However I calculated $ (a,0),(a,\pi),(a,2\pi)$.
0
votes
3answers
58 views
Proofs on equilateral triangles
Let $\Delta$ be the set of all triangles with two equal edges and be inscribed in a circle of radius $R$.
So, how do I show that:
Equilateral triangle in $\Delta$ is maximizing the area?
and
this ...
2
votes
2answers
131 views
Hard proof concerning the periodicity of trigonometrical functions. Is that a challenge or just trivial
i want to know if exist or if you can develop or give me ideas of a proof to show that the least number for which sine is periodic is $2\pi$
$$\neg \{\exists n\in \mathbb{R} \wedge n < 2\pi: ...
4
votes
1answer
87 views
Is this a valid proof of the derivatives of the trigonometric functions?
For the sake of this proof, the trigonometric functions $\cos$ and $\sin$ are defined as the coordinates of a point on the unit circle, rather than any of the modern analytic definitions.
Let $\vec ...
1
vote
2answers
89 views
Can find the angles of the triangle created by 3 points if I have each points compass bearing?
I am currently researching using magnetometers and radio field strength of 3 points for localisation. Is it possible to use the compass heading of 3 points to work out the angles of the triangle they ...
8
votes
3answers
104 views
How to prove $\cos\left(\pi\over7\right)-\cos\left({2\pi}\over7\right)+\cos\left({3\pi}\over7\right)=\cos\left({\pi}\over3 \right)$
Is there an easy way to prove the identity?
$$\cos \left ( \frac{\pi}{7} \right ) - \cos \left ( \frac{2\pi}{7} \right ) + \cos \left ( \frac{3\pi}{7} \right ) = \cos \left (\frac{\pi}{3} \right ...
0
votes
0answers
19 views
Distance from a point outside of a sphere to two related points on the sphere, also angles needed
I'm a chemist with a solid background in maths, but I would really appreciate some help with the following problem:
I have a point $M$ and a sphere. I only know the distance from the point $M$ to the ...
3
votes
1answer
58 views
$\tan B\cdot \frac{BM}{MA}+\tan C\cdot \frac{CN}{NA}=\tan A. $
Let $\triangle ABC$ be a triangle and $H$ be the orthocenter of the triangle. If $M\in AB$ and $N \in AC$ such that $M,N,H$ are collinear prove that :
$$\tan B\cdot \frac{BM}{MA}+\tan C\cdot ...
3
votes
2answers
71 views
$\sin{\frac{A+B}{2}}+\sin{\frac{B+C}{2}}+\sin{\frac{C+A}{2}} > \sin{A}+\sin{B}+\sin{C}. $
Help me please to prove that:
for any $\triangle ABC$ we have the following inequality: $$\sin{\frac{A+B}{2}}+\sin{\frac{B+C}{2}}+\sin{\frac{C+A}{2}} > \sin{A}+\sin{B}+\sin{C}. $$
It's about ...
0
votes
1answer
25 views
The law of cosines for a sphere
$\cos(c) = \cos(a)\cos(b) + \sin(a)\sin(b)\cos(C)$
Prove that if $a$, $b$, and $c$ is approximately $0$, then $c^2 = a^2 + b^2 - 2ab~\cos(C)$.
I wasn't sure how to prove this. One thought I had was ...
3
votes
5answers
151 views
elegant proof that $\sin(x)\cdot\cos(x)=\sin(2x)/2$
I tried for a few days to prove the identity $\sin(x)\cos(x)=\frac{\sin(2x)}{2}$ and finally got the following proof. I wanted to know if someone knew a simpler or more elegant way to proof it.
...
0
votes
2answers
42 views
Area of a rectangular triangle
We need to calculate the area of the triangle shown in figure:
The text of the problem also says that: $\sin \alpha =2 \sin \beta$. What is the area of the triangle?
1
vote
0answers
114 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
72 views
A controlled trapezoid transformation with perspective projecton
I'm trying to implement a controlled trapezoid transformation in Adobe Flash's ActionScript using the built-in perspective projection facility. To give you an idea of how the effect looks like:
...
1
vote
1answer
59 views
Area of a Quadrilateral proof
Prove that the area of a quadrilateral is one half the product of the lengths of its diagonals and the sine of the angle between the diagonals.
2
votes
2answers
48 views
Duplicate quadratic Bézier curve with new start point?
I have Bézier curve as shown by the wikipedia gif here:
I would like to create a new curve that is a segment of the old one. For example, in this gif (from the same article):
.. if I wanted B to ...
2
votes
2answers
152 views
The distance from a point to a line segment
I'm pretty sure this may be a duplicate post somewhere, but I've searched all through the internet looking for a definite formula to calculate the distance between a point and a line segment. There ...
2
votes
1answer
47 views
Finding the coordinates of a point five units along the line perpendicular to a midpoint?
I've been doing some personal math stuff and have spent the last few hours trying to figure this out with no success.
I want to find the coordinates of the point at the end of the small line segment
...
2
votes
1answer
134 views
Trigonometry / Geometry Puzzle with a Circle Inscribed within a Square
Point P is any point on the inscribed circle. You must prove that
(tan(a))^2 + (tan(B))^2 = 8
I first moved point P down to the point where the square would be tangent to the curve to make the ...
1
vote
1answer
32 views
Given a unit circle, is there a diameter that intersect it in one single point?
This is false but this is what I have come up with:
The circle can be written as $x=\cos\phi$, $y=\sin\phi$, $\phi \in \left [ 0,2\pi \right ]$
Denote now $t=\tan{\frac{\phi}{2}}$ and it follows ...
0
votes
2answers
78 views
radian measure problem help.
Find, in radians, the angle between the tangents to a a circle at two points whose distance apart, measured on the circumference of the circle is 350 ft., the radius of the circle being 800 ft.
so ...
0
votes
1answer
41 views
Determine theta/radius line parameters from line segment endpoints
I've been working on this for the past few hours and am quite stuck!
As part of a computer vision exercise I've build a Hough transform that maps between the (x,y) space of an image, and a parameter ...
2
votes
1answer
99 views
Trigonometry and Geometry
I have no idea on how to solve this question so can someone please assist me. My son brought it from school and he is really struggling with the question.
Consider a triangle ABC with line segments ...
