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Projecting a line segment onto a plane |
2000-06-08 |
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From Monica:
What is the measure of the angle determined by a 14 inch segment and its projection into a plane if the length,in inches, of the projection into the plane is 7 inches?
Answered by Penny Nom. |
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Surface area of a contact lens |
2000-06-06 |
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From Evie Contreras:
I would like to know how to calculate the surface area of a contact lens with a radius of 7mm? I know that the area of a circle is pi R squared, but a contact lens has a dome.
Answered by Harley Weston. |
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8 Queens on a Chess Board |
2000-06-06 |
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From Patrick McGarrity:
In the classic puzzle where you put 8 Queens on a chess board and no queen can take any other queen, I was wondering if there was multiple solutions. Obviously there's the mirror and opposite images of the way I solved it, but I was wondering how many solutions there were, and if these solutions all followed a similar pattern?
Answered by Claude Tardif. |
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Divisors of 2000 |
2000-06-06 |
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From Amanda Semi :
- find the product of all the divisors of 2000
- dog trainer time has 100m of fencing to enclose a rectangular exercise yard. One side of the yard can include all or part of one side of his building. iff the side of his building is 30 m, determine the maximum area he can enclose
Answered by Claude Tardif. |
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Problems |
2000-06-06 |
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From Debbie Cummins:
I am a Mum of a 12 yr.boy needing help with some math problems. I need not only the answers but how it is worked out. - Both the leftmost digit & the rightmost digit of a 4 digit number N are equal to 1. When these digits are removed, the 2 digit number thus obtained is N div by 21 Find N.
- Find all 3 digit even numbers N such that 693xN is a perfect square, that is, 693x N = k x k where k is an integer.
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Answered by Paul Betts and Claude Tardif. |
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Writing in Math |
2000-06-05 |
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From Laurel:
How can I incorporate writing into my math curriculum?
Answered by Penny Nom. |
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A derivative problem |
2000-06-04 |
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From Jeff Ellis:
If F(x)=(4+x)(3+2x2)2(2+3x3)3, find F'(0)
Answered by Harley Weston. |
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Percents with mixed numbers |
2000-06-04 |
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From Julie:
How would you find the percent of 33 1/3 out of 90 by using fraction settup!I can do whole numbers but not mixed. This is how to do whole numbers say it was 33 of 90 33 x 90 = 2970
100 x 1 = 100
2970 divided by 100
the answer is 29.7 so how do you do it with a mixed number
Answered by Penny Nom. |
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Pi to 5 decimal places |
2000-06-03 |
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From Emily:
The question is find the value for pi to 5 decimal places????
Answered by Penny Nom. |
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A centroid problem |
2000-06-02 |
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From Kerstin:
An isoceles triangle has sides measuring 13 cm, 13 cm, and 10 cm. Find the distance from the centroid to the vertex of a base angle.
Answered by Harley Weston. |
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4 Color map Theorem |
2000-06-02 |
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From Rick Slen:
I am challenging my students to find a map that can not be coloured using only 4 colours. I know that it is not possible, but one boy drew a map with a "country" totally surrounding all the others so of course it touched all other colours. How do I explain that this type of map is not permissable?
Answered by Denis Hanson. |
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1+4+9+16+...n^2 = n(n+1)(2n+1)/6 |
2000-06-01 |
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From Shamus O'Toole:
How do you derive that for the series 1+4+9+16+25.. that S(n)=(n(n+1)(2n+1))/6
Answered by Penny Nom. |
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Sens d'un mot |
2000-06-01 |
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From Edward Brisse:
Serait-il possible de connaître le sens précis du mot "PORISME". Exemple : "le porisme de Poncelet".
Answered by Claude Tradif. |
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Using the inverse sine function |
2000-05-31 |
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From Nelson Rothermel:
This has me completely baffled. I have to use the laws of sine or cosine to find the angles of a triangle when I have 3 sides, so I can't go 180-x-y when I have 2 angles. Now, I have a triangle with values of 3, 7, and 9. Here are the steps I used (A,B,C are angles; a,b,c are opposite sides): angle A (16.1951 degrees): cos-1*((b2+c2-a2)/(2*b*c))
angle B (40.6011 degrees): sin-1*(b*sin(A)/a)
angle C (56.7962 degrees): sin-1*(c*sin(A)/a) If you notice, A+B+C does not equal 180. According to the book, A and B are correct, but C is supposed to be 123.2038 degrees. Why doesn't it work???
Answered by Harley Weston. |
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Powers of i |
2000-05-24 |
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From Paul Fieldhouse :
What is the result of raising i to the googol power? is there a rule or pattern to raising i by increasing powers of 10?
Answered by Penny Nom. |
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