







A semi ellipse 
20170725 

From Ian: The arch of the bridge is in the shape of semi ellipse,with its major axis at the water level.suppose the arch is 20ft. High in the middle,and 120 ft. Across its major axis. How high above the water level is the arch,at a point 20 ft.from the center (horizontally). Round of 2 decimal places Answered by Penny Nom. 





A deck that is half an ellipse 
20160228 

From Steve: On your website, I was reading a question and your response from a girl named Angela in which you provided a formula by which her father, a welder, could figure out points on an arc corresponding to equal 3' intervals on a 30' chord where the vertex was 1' off the chord. Is there an equivalent formula when working with an ellipse? I suspect this change will make the calculations significantly more complex. I am building a deck that is half an oval, and would like to be able to mark out the perimeter by measuring the distance from regular intervals on the primary access to a corresponding point on the perimeter. I will then connect the points on the perimeter and cut a reasonably smooth arc. The length of the primary access will be 22' and width of the deck at the vertex is 9'. I would like to be able to know the distance from the primary axis to a point on the perimeter at equal intervals of 6" along the primary axis. Can you help? Answered by Penny Nom. 





Slicing through a cone to form an ellipse 
20130806 

From Pulkit: we get an ellipse on slicing through a cone. Is there a relation between central axis of the cone and this ellipse?
Does it pass through the any of the foci of the ellipse? Answered by Chris Fisher. 





A curve in 3space 
20130214 

From pardeep: we have to show that the curve r(t)=(cos t)i+(sin t)j+(1cos t)k ,0<=t<=2pie;
is an ellipse by showing it to an intersection of a right circular cylinder and a plane.
i got the eqn. of the cylinder but did not get the eqn of plane. Answered by Harley Weston. 





A sundial on an elliptical cylinder 
20090722 

From Leo: I want to build a sundial where the shadow falls on an elliptical cylinder. I can
calculate the coordinates of the points on the cylinder that I want to mark.
My problem is that I will have to make the surface as a flat sheet and bend it
into an elliptical shape. However, I cannot work out a scheme to transfer
the coordinates I know into a distance that will work when I bend the shape.
Help! Answered by Robert Dawson. 





The center of an ellipse 
20090421 

From Nae: what is the ellipse center of 5x^2+3y^2=15 Answered by Stephen La Rocque. 





A crosssectional area 
20081113 

From David: I am doing a science project examining the tensile strength of seaweed fronds. I need to calculate the crosssectional area from the major and minor diameters of the elliptical central axis of the seaweed frond. What formula would I use to get this.
The strength of the segments is expressed in terms of crosssectional area of the frond at the test site. Answered by Penny Nom. 





An arch is in the form of a semi ellipse 
20081103 

From jessica: An arch in the form of a semi ellipse has a span of 10 meters and a
central height of 4 m. Find the heights of the arch at a point of 3 meters from the semi minor axis. Answered by Penny Nom. 





Does an oval have sides? 
20081002 

From reid: My 6 yo neice came home with her math homework and she was supposed to identify which objects had sides.One of the objects was an oval.I don't believe it has sides because it is curved and I don't think that would make it an object with sides.What would be the correct answer?Thanks,Reid Answered by Janice Cotcher. 





Eccentricity of an Elliptical Orbit 
20080820 

From Gina: A satellite has an elliptical orbit around the earth with one focus at the earth’s
center, E. The earth’s radius is 4,000 miles. The highest point that the satellite is
from the surface of the earth is 800 miles, and the lowest is 200 miles.
What is the eccentricity of the satellite’s orbit? Answered by Janice Cotcher. 





An ellipse and circle with the same area 
20080609 

From Michael: The area of the ellipse if equal to the area of a circle with radius=40 ft.
Find the values of a and b using appropriate algebraic techniques, not basic math computations.
A=pi ab and satisfy the constraint a+b=100???? Answered by Penny Nom. 





The standard form of an ellipse 
20080430 

From Rebecca: I have to write the following equation into standard form of an ellipse:
9(X1)^2 + (Y+1)^2 = 1 Answered by Stephen La Rocque and Harley Weston. 





The surface area of an ellipse 
20080225 

From paritosh: how is the surface area of a elliptical dome be calculated when the two diameters are 55 metres and 35 metres and the height of the structure is 13.4 mts? Answered by Harley Weston. 





Can't find circumference of an ellipse 
20070706 

From Michele: I need to figure the circumference of an oval and I know the height and width. Answered by Penny Nom. 





Finding the center of an ellipse 
20070620 

From Sima: find the center of the ellipse with the equation 3x^2 +4y^2+18x32y5=0 Answered by Penny Nom. 





The circumference of an ellipse 
20070525 

From Graham: I have an ellipse that I need to find the circumference of. It is 40ft at its longest point and 25ft at its shortest Answered by Penny Nom. 





Comparing the areas of various shapes 
20070516 

From Kathy: If the perimeters are the same, which has the greater area, a circle, a square, an ellipse, or an octagon? Answered by Stephen La Rocque. 





The foci of an ellipse 
20070327 

From Brad: I am trying to figure out how to find the foci of an ellipse x^2/7 + y^2/16 = 1.
Since 16 is the largest denominator I know the major axis is going to be the y axis.
Do I now take 7c^2=16. c^2=167, c^2=9, c=3. So is my foci (0,+3). Answered by Penny Nom. 





A circle is stretched horizontally by a factor of 2 
20070307 

From bob: I was wondering if you could double check my work?
the question is as follows: The circle X^2+y^22x3= 0 is stretched horizontally by a factor of 2 to obtain an ellipse what is the equation of this ellipse in general form? Answered by Penny Nom. 





The area of a ellipse 
20070125 

From Ranjit: I have a task in which i have to find the area of a ellipse. i find this difficult because i have only been provided with the perimeter, which is 1000m. Answered by Chris Fisher. 





How do I determine the length of an ellipse if the width and area are known? 
20070104 

From Tom: How do I determine the length of an ellipse if the width and area are known? Answered by Steve La Rocque and Karen McIver. 





Conic sections 
20061119 

From Joyce: My son has a project on conic sections. I need the following information on Parabola, Circle, ellipse,and hyperbola. He can't find the following information for each conic section: equations with explanations, four uses for each shape and Shape explanation. Answered by Penny Nom. 





Some applications of conic sections 
20061113 

From Burt: how are circles, ellipses, and hyperbolas used in everyday life Answered by Penny Nom. 





The area of an oval 
20061008 

From Bruce: area of an oval: 60" x 120" Answered by Stephen La Rocque. 





The focus of a parabola 
20061001 

From Lily: I have a mathematical assignment which includes applications of parabolas, hyperbolas and ellipses in the real world. I have been searching the internet and now I am ware that most of the applications of parabolas have a connection with what people call "the focus". However, I do not think I clearly understand what "the focus" of a parabola is. Would you please explain it to me? Answered by Penny Nom. 





The perimeter of a pool 
20060605 

From Troy: How many Linear feet would a pool be if the pool was 18 by 38 foot oval Answered by Penny Nom. 





A cone with an oval as base 
20060301 

From Richard: I am trying to find the volume of a cone that is not round but oval. Answered by Penn Nom. 





Elliptic trigonometry 
20050915 

From Krystal: I'm currently searching for a science project topic and i have the idea of deriving elliptic trigonometry analogous to circular trigonometry. My questions are:
Is this project "possible" to do? Answered by Chris Fisher and Harley Weston. 





The equation of an ellipse 
20050717 

From Allan: I working on a problem that asks me to give the equation of an ellipse when only the location of the directrix and the length of the latus rectum are given. No other points on the ellipse are given. Again, the only "givens" are:
Length of latus rectum = 12
Location of directrix is x = 16
If I could determine the eccentricity, I could proceed from there by taking the ratio of the distance from a focus to the latus rectum point to the distance of the point from the directrix, but I lack the x coordinate of c. I've searched the text, and feel I've "missed something" somewhere! I note that the latus rectum segment is unique in one respect in that it is parallel to the directrix, where any other line segment on the ellipse to the focus would not be. Please indicate where I'm going wrong. Answered by Chris Fisher. 





The circumference of an oval pool 
20050518 

From John: I have an oval pool of which I am trying to find the circumference. it is 38 feet long and 19 feet wide Answered by Penny Nom. 





Quadratics 
20050105 

From Usman: Hi, in my Grade 11 Functions math class we have been assigned the task of finding jobs and careers related to quadratics, I have done many searches but have been unsuccessful, then I saw your website and emailed. I also have to use an example of a math problem that the job uses, then solve it, this will all compile on bristol board for a presentation. I would greatly appreciate it if you could send me some links and references of sources that refer to this subject. Answered by Harley Weston. 





An elliptical table 
20050103 

From Roger: Want to make an elliptical table, say the long (major) axis is 4 feet, and the short (minor) axis is 3 feet. I can construct this figure, but I'm trying to figure out what the exact dimension of a rectangle within this ellipse will be if I make the table a drop leaf type where the drop dimensions are equal for each end of both the long and short axes. Intuitively, it looks like there is one and only one solution. Answered by Penny Nom. 





An elliptic cone 
20040224 

From Ben:
I am building a model for my architecture class. I need to build a elliptic cone out of chipboard and i have no idea how to do this.
The cone needs to be 20in tall and the ellipse has a max radius of 10in and a min radius of 8in.
So my question is how do i lay this out on a piece of paper so that i can form the cone after i cut it out.
Answered by Penny Nom. 





An elliptical race track 
20031216 

From Judy: the inner rail of a race track is a perfect ellipse. the track is a standard width all the way around. how can i prove that the outer rail is a ellipse? Answered by Penny Nom. 





Uses of conic sections 
20030401 

From William: My name is William and I am doing a research paper on conic sections for my 12th grade math class. Part of the project is to find two conic sections in our world today and explain what there purpose is. I really need help in this area because I've been searching the internet for where conic sections are used in our world today and I really can't find anything. If you can tell me specific building or a pyramid that contains conic sections that would be great. Or even something in the universe would be helpful. Answered by Leeanne Boehm. 





The intersection of conics 
20021219 

From Glenda: We are studying systems of equations where two conic sections are the two equations that we are solving simultaneously. We were studying the number of solutions that are possible if you have an ellipse and a parabola. We all agree that there can be none, one, two, three or four solutions. The question that the students had for me was whether or not a portion of an ellipse and a parabola can overlap and thereby allow an infinite number of solutions. What should I tell them? Answered by Chris Fisher and Harley Weston. 





A paper model of a cone 
20020814 

From Bruce: I have made a paper model of a cone, cut a sloping section, and removed the top. I have drawn the major and minor axis on the paper surface of the section. The major axis is not symmetrical about the minor axis. To me, this is not an ellipse. To me, an ellipse is a tubular section, because this gives a symmetrical major axis. What is your opinion? Answered by Walter Whiteley and Chris Fisher. 





A polygon inscribed within an ellipse  Part 2 
20020708 

From Steven: I recently sought your advice about a problem that I have been working on for eight years or so concerning a polygon inscribed within an ellipse. I think that I may have confused matters by the way in which I put the question and hope that the enclosed diagram will clear matters up. In the ellipse below I have drawn three chords inscribed within one quadrant ( this would pertain to a twelve sided figure within the whole ellipse). These chords are exactly the same length as each other, for example if the major axis of the ellipse was 360 and the minor axis 240 I have worked out that a twelve sided figure would have sides of 78.2487. However I worked this out empirically with a method that could only be described as gruelling I would be most grateful if you could tell me of a method that would work for any ellipse and any number of sides. Answered by Chris Fisher. 





An equalateral polygon inscribed within an ellipse 
20020630 

From Steven: How would you calculate the length of one of the sides of an equalateral polygon (of n sides) inscribed within an ellipse ( of any eccentricity ) where all of the vertices exactly touch the perimeter of the ellipse? I know that when the eccentricity is zero ( i.e a circle ) the formula: r * (sin(180/n) * 2) will suffice. But what about when the eccentricity is greater than zero? Answered by Chris Fisher. 





A cone in 3 space 
20020320 

From Matthew: Let C in R^{3} be the cone defined by x^{2} + y^{2}  z^{2} = 0 (A) Let P be the plane described by x + 2z = 1 (i) Find a description of P in terms of two parameters s and t . . . Answered by Walter Whiteley. 





The perimeter of an ellipse 
20020214 

From Harry: I am planning to build a coffe table with an ellipse of 24x36 for the top. I wish to decorate the edge and need to know the lenght of the perimeter for lay out purposes. Is there an easy way to approximate this figure with out using intergal calculus? Answered by Penny Nom. 





An egg shaped island 
20010922 

From Karen: I am a civil engineering designer trying to design an egg shaped island. I want a 30' radius at the top and a 40' radius at the bottom and the longest length of the egg to be 125'. Is there standard geometry for an egg shape? I am not held to exact radii or the length given. Answered by Chris Fisher. 





Arclength of an ellipse 
20010703 

From A hobbyist: What is the equation (with the length of the arc as a variable) for one quadrant of the ellipse,... Answered by Claude tardif. 





The diameter of an oval 
20010523 

From Tim: Is there a such thing as a diameter of a oval? If not, is there a way to get the circumference? Answered by Claude Tardif and Penny Nom. 





Circles, ellipses, parabolas and hyperbolas 
20010509 

From Colleen: How is an ellipse like a circle? In what way does an ellipse have a center? How is a hyperbola similar and different to an ellipse? How is a parabola similar a different to a circle ellipse and parabola? Answered by Pnny Nom. 





An elliptic tunnel 
20010324 

From Janna: A tunnel is built under a river for a road 12m wide with a 2m sidewalk on either side. The top of the tunnel is semielliptical. A local bylaw stipulates that there must be a clearance of at least 3.6m at all points on the road. If the smallest possible ellipse is used, find the clearance at the center of the road. Answered by Harley Weston. 





Area of an ellipse 
20000502 

From Kaushal Shah: How do I Calculate the area of a ellipse known the length of any related thing. Example, suppose if I know the length of latus rectum, major&minor axis etc. Answered by Walter Whiteley. 





Perimeter of an ellipse 
20000221 

From Kurtis Proffit: What is the formula for the perimeter or circumference of an ellipse? Answered by Chris Fisher. 





Cleaning an Ellipse 
19990729 

From Mark Salter: Hello hope some one can help. We need to clean an elipse and then paint it. We need to know the square foot of the job and the job is an elipse which rises 2 ft. is 12 ft wide and is 36 ft long. Answered by Harley Weston. 





Foci of an Ellipse 
19970122 

From David Gilliam: How do I find the focii of the following equation? 4x^2 + 9y^2 = 36 Answered by Harley Weston. 





exercice! 
20050928 

From Un eleve: soit x et y deux nomres réels telque:
1 ≤ x^{2}x*y+y^{2} ≤ 2
1) Montrer que: 2/9 ≤ x^{4}+y^{4} ≤ 8
2) Montrer que: x^{2*n}+y^{2*n} ≥ 2/3^{2*n} telque n est un nombre entier naturel et n≥3.
Answered by Chris Fisher. 

