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A |
1999-05-02 |
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Leah pose la question : a=b a^2=ab a^2+b^2=ab-b^2 (a-b)(a+b)=b(a-b) a+b=b b 2=1 why is this proof wrong? Penny Nom lui répond. |
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A rhombicosidecahedron |
1999-04-30 |
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Himmat pose la question : What is a rhombicosidecahedron? Harley Weston lui répond. |
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Roman Numerals |
1999-04-29 |
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Michelle Jenkinson pose la question : Someone proposed this question to me and I do not know the answer, so I was wondering if you could help. How, using Roman Numeral, did people add, subtract, multiply, and divide with no zero or negative numbers? Penny Nom lui répond. |
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An equilateral triangle on a square |
1999-04-26 |
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Ed pose la question : My Grade 8 class and I were discussing the solution to the following problem: What is the area of the largest equilateral triangle that can be drawn on a 5 cm square. We used 5 cm as the base of our triangle and then drew the other two legs of 5 cm each to make the equilateral triangle. We then drew an altitude from the upper vertex to the base of the triangle. Using the law of Pythagoras with side a of 2.5 and side c of 5 we calculated side b to be 4.3 cm (the altitude). Therefore the area of the triangle would be 5 x 4.3 divided by 2 or 10.75 square cm. The answer key to this resource says I am wrong. What do you think? Have we interpreted the question incorrectly? Chris Fisher and Harley Weston lui répond. |
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A bike race |
1999-04-23 |
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Bill Gepford pose la question : Bill was in a bike race and his friend kyle calculated that if he went 15mph that he would cross the noontime checkpoint one hour early but if he rode 10mph he would arrive one hour late. How far away is the checkpoint? Penny Nom lui répond. |
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Question about 3rd degree polynomials |
1999-04-23 |
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Patrick Bryan pose la question : What is the general solution to the equation with the form: a*x^3 + b*x^2 + c*x + d = 0 I have once seen a solution to this a few years ago, but I do not recall if it was a general solution. What I do know, is that you could simplify this equation to: a*x'^3 + p*x' + q = 0... Doug Farenick lui répond. |
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Parallel and perpendicular lines |
1999-04-23 |
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Crystal Pilling pose la question : My name is Crystal Pilling and I am in 9th grade algebra. We are currently studying parallel and perpendicular lines. I am having trouble with this problem: 3/4x - 5y= 16, (5,-6) I have to find a line that is perpindicular to this line on a graph. HELP ME PLEASE!!!!! Penny Nom lui répond. |
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Bill and Sam at the Casino |
1999-04-23 |
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Rham Stewart pose la question : Bill and Sam went off to bet at the casino. Each started with the same number of dollars. At the end of the first hour, Bill had won 20$ and sam had lost 20$. At the end of the second hour, BIll had lost two thirds of his money, and Sam had won the same amount that Bill had lost. At that point, sam had four times as much money as BIll. How much did each one start with? Penny Nom lui répond. |
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Radius of an arc |
1999-04-22 |
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Rusty Riddleberger pose la question : I need to find the equation for finding the radius of an arc; I know the length of the arc (i.e the distance of the line connecting the two ends of the arc) and the height; (i.e the rise of the arc at its apex,) I had the formula years ago but it has lost me; this would be invaluable for work in new homes i.e. where we need to build an "arch" with a rise of 21" between two columns 11 feet apart Chris Fisher lui répond. |
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Shopping at Wegman's |
1999-04-22 |
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Stan pose la question : Joanne, Steve, Pat, Alice, Joan, and Bill go to Wegman's at the same time. Joanne buys 2 gal of milk, 1 dozen oranges, 8 apples, and 2 lb. of ground beef, paying a total of $13.24. Steve buys 3 qts. of milk, 5 lbs. of ground beef, 10 lb. of potatoes, and 2 bags of mixed vegetables, paying a total of $16.95. Pat buys 3 gal. of milk, 2 dozen oranges, 1 dozen apples, 5 lb. of potatoes, and 5 bags of mixed vegetables, paying a total of $25.09. .... Find the cost of: 1 qt. of milk, one orange, one apple one lb. of ground beef, one lb. of potatoes, and one bag of mixed vegetables. Penny Nom lui répond. |
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A ladder problem |
1999-04-22 |
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Michael Blade pose la question : There is a cube box 3feet x 3feet x 3ft resting against a vertical wall on level ground. Resting against the outside corner of the box is a ladder 10 feet tall, this ladder is of course resting on the ground but also against the outside corner of the box and rests on the wall. The question- the ladder is divided into two unequal section bounded by the box to the ground and the box to the wall. what are those dimensions? Penny Nom lui répond. |
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Area of a triangle from vertex coordinates |
1999-04-21 |
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Mark Tyler pose la question : I'm no schoolkid, but I liked your answers about triangles. You might enjoy a quick look at this, the kids may too. I was working on a Voronoi dual where I had to calculate the areas of very many triangles expressed as vertex coordinates, so I derived the following very direct formula: A = abs((x1-x2)*(y1-y3)-(y1-y2)*(x1-x3)) for triangle (x1,y1)(x2,y2)(x3,y3) I've never seen this in a textbook. Is it original? I doubt it, the proof is only a few lines long. Regardless, it may be fun for the kids, even if it's not on the curriculum. Walter Whitley lui répond. |
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Radius of convergence |
1999-04-21 |
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Nowl Stave pose la question : Why is the radius of convergence of the first 6 terms of the power series expansion of x^(1/2) centered at 4 less than 6? Harley Weston lui répond. |
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Circles |
1999-04-21 |
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Alex Elkins pose la question : How do you find the circumference of a circle if you only know the radius and the square feet or inches of the circle if the radius is 18 inches, If done in inches do you multiply by 12 to get the square feet? Jack Lesage and Harley Weston lui répond. |
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The average rate of change of a function |
1999-04-20 |
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Tammy pose la question : Suppose that the average rate of change of a function f over the interval from x=3 to x=3+h is given by 5e^h-4cos(2h). what is f'(3)? I would appreciate any help with this question. Harley Weston lui répond. |
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