







Points on the xaxis 
20150314 

From Justin: jamie tells her friend that ordered pairs that have an xcoordinate of O line xaxis. She used the origin as an example. Describe Janine error. Use a counterexample to explain why Janine statement is false Answered by Penny Nom. 





A region described by inequalities in cylindrical coordinates 
20150221 

From Rahul: I am not able to visualize a solid given by inequalities as under (in cylindrical coordinate system)
0=
I know that (can visualize) first 2 inequalities say it is a cylinder of infinite length.
It seems that third inequality poses the restriction to the height as well as it makes us to remove a cone.
But I just can not understand it clearly.
Thanks in advance!
Regards,
Rahul Answered by Penny Nom. 





Equal ordinate and abscissa 
20130815 

From sonit: the slope of tangent to the curve y=(4x^2)^1/2 at the point, where the ordinate and abscissa are equal, is Answered by Penny Nom. 





r=10cos(t) in cylindrical coordinates 
20130518 

From r.m: question from calculus exam: what is the figure obtained having eqn.r=10cos(t) in cylinderical coordinates?
i know it is a cylinder with center (5,0) ,but can't the equation represent two cylinders ,one with center
(5,0) and the other with center (5,0).
thanks for any help. Answered by Penny Nom. 





Polar coordinates 
20100414 

From Lan: Given the rectangular equation (x^2)+2x+(y^2)+y=0, find the polar equation. Answered by Harley Weston. 





Integration of cos (x^2+y^2) dx dy 
20100212 

From anna: How do you evaluate the integration of integration of cos (x^2+y^2) dx dy? Answered by Tyler Wood. 





The line through D(4, 0) and E(2, 6) 
20091116 

From Rogerson: The point F is on the line through D(4, 0) and E(2, 6) so that DF=4DE. Find the coordinates of F. Answered by Penny Nom. 





A side of a rectangle 
20090715 

From hanbal: Could please help solving this problem
A(1,3) and D(5,5) are two vertices of a rectangle ABCD. The equation of line AC is 3y=4x + 5
Find
a) the equation of line DC Answered by Chris Fisher. 





Subdividing a foursided lot 
20090327 

From kannan: i have a 1.5 acre land having four sides
AB=64.8 meters
BC=94.2 meters
CD=54.4 meters
DA=127.2 meters
angle at D is 90
the side AB (frontage)is road facing i want to split the plot in to two halves
having same almost area and almost equal frontage, kindly help me, if possible
explain with drawing.
Regards
Kannan Answered by Harley Weston. 





Cutting a pipe at an arbitrary angle 
20080920 

From John: from the original question Al asked about cutting a 200 diameter pipe in 45 degrees. can someone explain the math steps required to creating the graph. I am trying to do the same thing only using a 150 degree cut. Answered by Harley Weston. 





Vectors and an orientation change in the axes 
20080830 

From moumita: what differences take place to a vector because of choice of orientation of the coordinate axes and why?? Answered by Harley Weston. 





A regular hexagon 
20080520 

From Martin: Given a regular hexagon with center on the origin of an xy plane with coordinate (r,0) on the x axis, we are to express the coordinates of "A" located at 120 deg from (r,0) in terms of "r". Answered by Janice Cotcher. 





Three points on the circumference of a circle 
20070730 

From Bharathi: given a circle with radius r and a point x,y on its circumference,output two other
points x1,y1 and x2,y2 on the circle so thar all 3 points form a equilateral triangle. Answered by Stephen La Rocque. 





What is the equation? 
20060913 

From A parent: HERE ARE THE COORDINATED (0,3), (1,0), (2,3),(3,6)
WHAT IS THE EQUATION? Answered by Penny Nom. 





Plotting coordinates on a number plane 
20060908 

From Victor: I need to plot coordinates (0,2), (2,2), (2,0), and (0,0) on a number or coordinates plane, I am not sure how to do this, and get lost after the first point, can you please help? Answered by Penny Nom. 





Polar to Cartesian coordinates 
20060115 

From Linden: How do you convert six units at 30 degrees Polar Coordinate into a Cartesian Coordinate? Answered by Penny Nom. 





Converting coordinates 
20041025 

From Allen: I am trying to help my son with his home, but I don't remember these conversions. Please help.
1. Convert the following coordinates
Cartesian x = 7, y = 24
2. Convert the following coordinates
Polar r = 4, theta = pi / 3 Answered by Penny Nom. 





Terminology 
20030831 

From Maria: My daughter Veronica is a rising 6th grader and has to complete some Summer Math assignments and would like to ask you three questions:  ___________ are number pairs that have a product of 1.
 You can name any point on a plane with two numbers. These two numbers are called _____________.
 A _______________ is the size of a cube that is exactly 1 inch on each edge.
Thanks, Answered by Penny Nom. 





A triangle in the complex plane 
20030710 

From Scott: The vertices O and A of an EQUILATERAL triangle OAB in the complex plane are located at the origin and 3 + 3i. Find all possible values for the complex number representing the vertex B. Give the location of B in both polar and cartesian form (to 2.d.p) Answered by Penny Nom. 





Transformations of pattern blocks 
20030206 

From Cheryl: I am trying to help my 8th grade son with Transformations  use of patttern blocks. He has to trace a figure and reflect it across the xaxis, which I can do, but then it indicates include ordered pairs  that confuses me. Answered by Penny Nom. 





Counterclockwise 
20010914 

From Rolanda: When Descartes invented the coordinate system he decided to number them counterclockwise. Why? Answered by Chris Fisher. 





Polar coordinates 
20000224 

From Tran Trung: How do I convert r = 2/(2sin(theta)  3cos(theta)) to rectangular and x^{2} + y^{2} 2y = 0 to polar form? Answered by Harley Weston. 





A valentines project 
20000221 

From Courtney Dohoney: I was assigned a valentines project. Our job is to make a valentines card that has a math theme. On my valentines card I would like to include the set of equations that when graphed look like a heart. If you can figure out a set of equations and get it back to me I would be very happy. Answered by Harley Weston. 





A Polar Plot 
19990506 

From Irene: Consider the polar equation r=23Cos(theta/2) In the interval [o, 4Pi], how would you find the area of one of the leaves and also the length of one of the edges of a leaf? Answered by Harley Weston. 





Complex numbers/polar coordinates 
19990325 

From Kate Cegelis: What is the relationship between complex numbers and polar coordinates? Answered by Harley Weston. 





Intersection of planes 
19981122 

From Dave Rasmussen: I am a teacher of secondary mathematics with a question about the uses of Three Dimensional Coordinate Geometry. I have been teaching my students to write equations of planes and lines,  to find the intersection of these and the distance between them. What I am having difficulty finding are good applications of these techniques to "real world" situations. Can anybody help me? Answered by Walter Whiteley and Harley Weston. 





Calculating the Intersection Point. 
19971210 

From Milton Parsons: Given 2 lines through (x1,y1),(x2,y2),and (x3,y3),(x4,y4). Can you give me a good formula for calculating the intersection point. I would greatly appreciate it.Thanks. Answered by Chris Fisher and Penny Nom. 





A Geometry Problem 
19970918 

From Rebecca Henry: A circle is centered at the vertex of the right angle of an isosceles triangle. The cirlce passes through both trisection points of the hypotenuse of the triangle. If the length of a radius of the circle is 10, find the area of the triangle. Answered by Chris Fisher Harley Weston. 





Yaxis 
19970529 

From Leah: I know that the proper name for the X axis is the abscissa, but, what is the proper name for the Y axis? Answered by Chris Fisher. 

