







A common tangent to two general parabolas 
20151115 

From Kind: Hi,
I want to find the common tangent of two general parabolas, but i don't know if it's possible or not.
If it's possible, please make a tutorial.
The first parabola equation : Ax^2 + Bxy + Cy^2 + Dx + Ey + F = 0.
The second parabola equation : Gx^2 + Hxy + Iy^2 + Jx + Ky + L = 0.
I need this because i want to find the equation of Beloch fold. (Huzita  Hatori 6th axiom)
However if you know any other method to find Beloch folds equation, I am open for any suggestions. Answered by Chris Fisher. 





A parabola 
20120604 

From Madeline: In a parabola, I need to know what "a" b and c determine. I think that a determines the width of the parabola, but I am not exactly sure what b, and c do. Answered by Robert Dawson. 





Sketch the graphs of the following 
20100302 

From musaf: without detailed plotting of points,sketch the graphs of the following
showing relevant information on the graphs:
a) y=(x3)2 +5
b)y=4xx2 Answered by Penny Nom. 





Graphing a parabola 
20090127 

From Kimberly: I need help with this parabola: graph y=5x^25x6. I am not really understanding how to graph parabolas in general. Can you help me? Answered by Penny Nom. 





x = y^2 and x = 4 y^2 
20070911 

From Jil: My question is when dealing with parabolas, x=y^2, so that they are sifted on their side you could say,
what will happen to the graph if you change it to x=4y^2. I understand
that the  flips the graph in the other direction but can you simply just plug
in numbers and increase the stretch of the y? Answered by Penny Nom. 





Parabolas in the real world 
20070518 

From Katherine: Hi, my name is Katherine, and my mean old math teacher just assigned us a test in which
we have to write two examples of how parabolas are used in the real world, each one page
single spaced, size 12!! I know you have already answered some questions like this, but
I still don't understand the whole baseball thing, and any other way parabolas are used.
And how I can write a whole page on it. But that's my problem, not yours, I just need help
with a little explanation on how parabolas are actually used today. I know this might be kind
of confusing for you, but imagine how it is for me!! Answered by Stephen La Rocque. 





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. 





A fountain of water jets forms parabolic arches 
20060503 

From Jennifer: Let's say in you have a fountain and the water jets form parabolic arches. The center of the fountain, being the origin of the coordinate system, it is elevated 5 feet off the ground, . The equation formed the water arch is y= x^{2}+4x, what is the radius of the basin needed to catch the water at ground level? Answered by Stephen La Rocque. 





Three parabolas 
20040424 

From A tutor:
I am a maths tutor. One of my year 12 students has given me this assignment. Many parts are ambiguous.
I am trying to determine the equation of the line segment AB. Given that A has an incline of 10 degrees below the horizontal, I am assuming that this parabola (although you can only see part of it) has been rotated 10 degree clockwise. Am I right in assuming this? If so, how do I derive the equation of the parabola as it will then not fit the general form y = ax squared +bx +c of a parabola.
Also, how is one expected to find the x coordinate of D without the equation of this parabola. To find the equation you need the xcoordinate and therefore be able to find another point on the parabola in order to derive the equation using simultaneous equations.
Answered by Penny Nom. 





A parabola 
20031024 

From Delores: Given the vertex (4, 2) y intercept = 6 find if/where the parabola crosses the x axis? Answered by Penny Nom. 





A circle, tangent to two circles and a line 
20030430 

From Keith: I have a horizontal line (that is treated as a datum line or the X axis), with two circles having their center points at different heights from that line (X1,Y1 & X2,Y2). The two circles are also at different diameters (R1 & R2). Both circles and the line (XAxis) do not intersect nor are they tangent. My goal is to determine the maximum diameter of an inscribed circle that will fit between all three. Answered by Chris Fisher and Harley Weston. 





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. 





How do you estimate the equation of a parabola? 
20021201 

From Audrey: How do you estimate the equation of a parabola? I have a project where a must find parabolas in magazines and then estimate their equation. Answered by Penny Nom. 





Determining a parabola 
20021106 

From Shelley: let (0,3) and (1,9)and (1,1) be given points in a parablola. Determine a b and c Answered by Penny Nom. 





Parabolas 
20020203 

From Kuang: Who is credited for working with or studying the Parabola? What is a conic section? What does a parabola look like? How is a parabola formed? Where and how are parabolas used today in the real world? Answered by Harley Weston. 





Quadratics 
20010516 

From John: I am in the final stages of a math project and I need to interview an expert for the last part. Please try to answer at least a few of these questions.  How do you use quadratic equations in your everyday life?
 Do you find being a math expert very helpful in life?
 Is the quadratic equation useful to you?
 Why did you decide to become a math expert?
 What do you think is the most important function of the quadratic equation?
Answered by Harley Weston. 





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. 





A suspension bridge 
20010324 

From Janna: The cables of a suspension bridge hang in a curve which approximates a parabola. The road bed passed through the vertex. If the supporting towers are 720m apart and 60m high, find: a) an equation of the parabola (it's y = ^{1}/_{2160}x^{2}) b)the height of the cables at a point 30m from the vertex. I substituted 30 in for the x value and got 0.42 and the answer is 42. What did I do wrong? Answered by Denis Hanson and Claude Tardif. 





The path of a cannonball 
20010115 

From A student: Artillerymen on a hillside are trying to hit a target behind a mountain on the other side of a river. Their cannon is at (x, y) = (3, 250) where x is in kilometers and y is in meters. The target is at (x, y) = (2, 50). In order to avoid hitting the mountain on the other side of the river, the projectile from the cannon must go through the point (x, y) = (1, 410). Write the equation for the problem. Answered by Penny Nom. 





Parabolas in life 
20001203 

From Ashley: I am a student and my teacher recently gave us the assignment of writing a portfolio on parabolas in life and finding examples, three to be in fact, only we have to go into detail about only one. We have been instructed to include such terms as: axis of symmetry, completing the square, parabola, quadratic formula, standard form (vertex form) and vertex. We also must include in our detailed example an equation of the parabola and very specific details, PLEASE HELP! Answered by Harley Weston. 





Bridges and parabolas 
20001118 

From Lauren: My name is Lauren, and Im a secondary school student in Ontario. For my gr11 advanced math class I have to find out how and why parabolics are used in arch bridges and write 3 paragraphs on it. People who cohse satelites and whatnot are lucky  I've found a ton of info, but for arch bridges there seems to be nothing. Answered by Harley Weston. 





A parabola problem 
20000323 

From Morin: I need to prove that if parabola x^{2}=4py has a chord (not necessarily a focal chord) intersecting it at points A and B, with tangents to the parabola at points A and B that intersect at C, then a line drawn through C and the midpoint of the chord M is parallel to the yaxis. Further, prove that the point D where this line intersects the parabola is the midpoint of line CM. Answered by Penny Nom. 





The Terror Run 
20000318 

From Danny Mclean: A fairground's most popular attraction is a roller coaster ride known as the Terror Run. One stretch of track is called the Missile Path and is in the form of a parabolic curve. B is 180m horizontally from A and the highest point of the curve is 100m above A and B. A.. The owner works out a quadratic expression to describe the Missile Path. What is the expression He found? B.. A safety Engineer examined the structure and observed that points A and B were likely to be damaged due to the steepness of the Missile path near these points. The owner can see no way to make the Missile path less steep near A and B and to keep the height of the ride the same. HOW CAN IT BE DONE? Answered by Harley Weston. 





Parabolic shapes 
19990504 

From Justin Ailor: Can you give me some parabolic shapes? Answered by Penny Nom. 





Satellite dishes 
19990210 

From Katherine Shaw: I have read your information on 'Why are satellite dishes parabolic", and I know the reciever should be placed at the focus of the parabola. Could you test this with lights beams and a parabolic mirror, or would light beams behave differently. Thanks. Answered by Jack LeSage and Harley Weston. 





The Left Side of a Parabola. 
19981020 

From Shay: Find the parametrized equation for the left half of the parabola with the equation: Y=x^24x+3 Answered by Chris Fisher. 





Parabolas 
19980724 

From Danica: how do you find the focus, vertex, and directrix of 4xy^22y33=0 Answered by Penny Nom. 





Polynomials 
19971007 

From Sheryl and Jeff: I'm a math teacher in Jerusalem, Israel. I'm teaching about graphing polynomial functions in a precalc class. A student asked me what they're good for. I couldn't give her a good example. Do you have one. Thanks. Answered by Penny Nom. 





The General Equation of a Parabola 
19970528 

From Michelle: My name is Michelle and I am a 10th grade student in algebra 2 w/ analysis. I am doing a report on parabolas and I need to know what the general equation is. I've looked in books and keep finding different ones! I also need to know how they can be used in nature. Thank you so much for your time. I really appreciate it!  Michelle Answered by Harley Weston. 





Parabolic Mirrors 
19970128 

From Megan Wennberg: Consider a ray of light that passes through a chord of a parabola (the chord is above the focus and parallel to the directrix), hits the parabola at a point (x,y) and is reflected through the focus. If d1 is the distance from the chord to the point of incidence (x,y) and d2 is the distance from (x,y) to the focus, can you prove that the sum of the distances d1+d2 is constant, independent of the particular point of incidence. Answered by Penny Nom. 

