







Proofs 
19970413 

From Daniel: I'm having trouble understanding proofs. I don't know how to come up the answers on my own. I search through the book looking for the answer. I understand what they are doing, but I don't know how to do it. Answered by Walter Whiteley. 





The Division Bracket. 
19970409 

From Judy Riley: A fellow teacher recently asked if I remembered the exact word for a division bracket (not the symbol with dots, the horizontal line in a fraction, or a solidus). I couldn't. Can you help? Answered by Walter Whiteley and Harley Weston. 





A Geometry Problem 
19970409 

From Gina M. Pisco and Rebecca Henry: Three segments of 3, 4, and 5 inches long, one from each vertex of an equilateral triangle, meet at an interior point P. How long is the side of the triangle? Answered by Richard McIntosh. 





Equation of a line 
19970408 

From Susan Gregson: I am a secondary school teacher. My students and I would like to know why the letters m and b are traditionally used to stand for slope and Yintercept in the standard form of an equation. Was this an arbitrary choice? Who made it? Are the letters from Greek ot Latin words? Answered by Harley Weston. 





Graphing Inequalities of Conic Sections 
19970324 

From James Sheldon: I'm trying to graph Systems of Conic Sections with inequalities, but I'm running into problems on which area to shade: x^2+y^2 is greater than or equal to 16 xy > 4 So I graph these two equations, and then my teacher said to substitute a point into it but I'm still not sure how to do it... Answered by Penny Nom. 





The normal distribution. 
19970321 

From Donna D.Hall: I am looking for a proof for the normal distribution. I suppose "proof" was not a good choice of words. What I am looking for is a way to "derive" the normal distribution in simple terms so that the most average teenager can see the logic. Can you help me? Answered by Harley Weston. 





Why QUADratic? 
19970319 

From Paula Miller: A student today asked me why a quadratic, with highest power of degree 2, was called a QUADratic. We're awaiting the answer with baited breath! :) Answered by Chris Fisher and Walter Whiteley. 





Mathematical Induction and the Derivative 
19970318 

From Shuling Chong: "Obtain a formula for the nth derivative of the product of two functions, and prove the formula by induction on n." Any educated tries are appreciated. Answered by Penny Nom. 





A Presidential Proof 
19970318 

From Greg Smith: Which US president developed a proof for the Pythagorean Theorem? Where can a copy of the proof be located? Answered by Chris Fisher and Harley Weston. 





The Real Pythagoras 
19970316 

From Michael Gaskin: I am wondering if you have any information about Pythagoras and his accounts in math. Answered by Chris Fisher. 





Ajax, Beverley, Canton and Dilltown 
19970314 

From S. Johnson: The following towns are placed on a coordinate system. Ajax at (x,z), Dilltown at (10,0), Canton at (0,0) and Beverly at (0,10). The roads from Beverly to Canton and from Canton to Dilltown are perpendiculat to each other and are each 10 miles in length. A car traveling at all times at a constant rate, would take 30 minutes to travel straight from Ajax to Canton, 35 minutes to travel from Ajax to Canton via Beverly, and 40 minutes to travel from Ajax to Canton via Dilltown. What is the constant rate of the car, to the nearest tenth of a mile per hour. Answered by Chris Fisher and Harley Weston. 





Names of the Polygons 
19970304 

From Manuel: What do you call a 13 sided polygon? Is there a list of the different names? Answered by Walter Whiteley and Harley Weston. 





0! 
19970302 

From Donna D. Hall: I am looking for a quick and easy explanation as to why 0! is 1. Answered by Walter Whiteley and Denis Hanson. 





Area Between Two Sectors 
19970302 

From Rebecca Henry: Points A,B,C,D,E,F are equally spaced on a unit circle. Arc CGE has a center A. Find the number of square units of area in the shaded region. Answered by Walter Whiteley. 





A Functional Equation. 
19970226 

From Ronald Lui: Find all functions f:S > S statisfying the two conditions: 1)f(x+f(y)+xf(y))=y+f(x)+yf(x) for all x and y in S 2)f(x)/x is strictly increasing on each of the interval 1 Answered by Saroop Kaul and Chris Fisher. 

