







A spaceship playhouse 
20100726 

From Dave: I would like to build a spaceship playhouse for my grandson I want it to
be about 36" around and I want to use 5/4 decking boards that measure
5 1/2" wide how do I figure out how to lay out a base pattern to nail to
(what angle do I need to cut and how many boards will it take to go around
the circle. Answered by Penny Nom. 





The triangle inequality 
20100111 

From Nazrul: If A and B are any two vectors, then how can I prove that magnitude of (A+B)<=magnitude of A+magnitude of B. Please show me the process in details. Thank you. Answered by Robert Dawson. 





A cardboard spaceship 
20080831 

From Lee: I am building a "cardboard" spaceship for my 4 year old grandson.
The cabin is a dishwasher box with a cool control panel and elipse shaped
windows.
I really need help designing the cone or"nosecone".
The diameter of the base is 26", 24" tall, with a 6" diameter opening
at the top.
Thank you for the help!
Lee Answered by Penny Nom. 





Dual spaces 
20011126 

From Hoda: In the book "Linear Functional Analysis" from Epstein there is a proof (page 116) of the following theorem: The dual space of L^{p} is equal to L^{q}. Later, it is stated as a theorem without proof that for 1 <= p < +infinite, The dual space of l^{p} is equal to l^{q}. Answered by Doug Farenick. 





Commas in numbers 
20010906 

From Mike: When did the Ontario Education system drop the use of commas in large numbers and replace with a space? Why? Answered by Walter Whiteley. 





Why the change from commas between every 3rd digit, to spaces instead? 
20010103 

From Clarende Duby: Why the change from commas between every 3rd digit, to spaces instead? For example: Three million three hundred thirtythree thousand three hundred thirtythree written like: 3 333 333 instead of 3,333,333? Does it have something to do with standardizing mathematical notation worldwide? Answered by Harley Weston. 





Networks of satellites and linear spaces 
20001208 

From David: Let us suppose some companies have collaborated to place several satellites in orbit. Let us call the set of all satellites that a given company helped place in orbit a network. Finally let us assume the following 4 rules.  There are at least two distinct satellites.
 For each pair of satellites there is exactly one network containing them.
 Each network contains at least two distinct satellites.
 For each network, there is a satellite not in it.
What is the least number of satellites. what is the least number of networks? Answered by Penny Nom. 





Parking spaces 
20001107 

From Lydia: A parking lot has 4 aisles. Each aisle is about 40 yards long and has parking places on both sides. If a parking place is 3 yards wide, how many cars can the parking lot hold? Answered by Penny Nom. 





Espaces vectoriels 
20020818 

From Bacar: Comment montrer que trois (ou plus que trois) sous espaces vectoriels sont en somme directe. Answered by Claude Tardif. 

