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A trig identity |
2010-01-24 |
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Natalie pose la question :
hi, i need help proving the following trig identity. i cant seem to figure out how to do it.
thanks so much.
(1+sin2x)/cos2x = cos2x/(1-sin2x)
Penny Nom lui répond. |
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An altitude of the triangle intersect a side of the triangle |
2010-01-23 |
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Sarah pose la question :
In what type of triangle does an altitude of the triangle intersect a side of
the triangle at its midpoint??
-Sarah
Walter Whiteley lui répond. |
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A sequence |
2010-01-22 |
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brahmaji pose la question :
0 7 26 63 _ 215 342 fill the blank? find the missing number
Robert Dawson lui répond. |
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A trig problem |
2010-01-22 |
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vinton pose la question :
ok there is a triangle labled q, p, r......the three towns p, q, r are such that the bearing of p from q is 070 degrees.
r is 10 km due east of q and pq = 5km.
(i) calculate correct to one decimal place, the distance of pr.
(ii) given that angle qpr 142 degrees, state the bearing of r from p
Penny Nom lui répond. |
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A 20% markup |
2010-01-22 |
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barbara pose la question :
i ran across the same question using 10%, my question is this, I have $751,400, which has been marked up 20%. I want
to know the original amount prior to mark up.... can you give me the formula.?
Penny Nom lui répond. |
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Arrays |
2010-01-21 |
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Raven pose la question :
Mary says that the greater the number of counters, the greater the number of different arrays you can form.
Give an example that shows that Mary is wrong.
Penny Nom lui répond. |
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The binomial theorem |
2010-01-21 |
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Laura pose la question :
Using the fact that (1 + x)^4 * (1 + x)^9 = (1 + x)^13 show (4C0 * 9C4 + 4C1*9C3 + 4C2*9C2 + 4C3*9C1 + 4C4*9C0) = 13C4
Harley Weston lui répond. |
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A 4-digit phone code |
2010-01-21 |
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pat pose la question :
my daughter can`t remember her 4-digit code to unlock her phone. she is pretty sure it starts with a 4. can you help us? my brain is locked up
Robert Dawson lui répond. |
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The volume of a silo |
2010-01-21 |
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heather pose la question :
The height of the silo is 30ft and the face that rests against a barn is 10 ft wide. If the barn if 5 ft from the center of the silo what is the capacity of the silo?
Penny Nom lui répond. |
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Odds and evens in an n by n+1 table |
2010-01-21 |
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Shankar pose la question :
The boxes of an n * (n+1) table ( n rows and n+1 columns) are filled with integers.
Prove that one can cross out several columns ( not all of them !) so that after this operation
all the sums of the numbers in each row will be even.
Robert Dawson lui répond. |
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A trigonometric equation |
2010-01-21 |
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Laura pose la question :
Find the exact solution for sin4t + √3sin4t = 0 for t when (o ≤ t ≤ π
Harley Weston lui répond. |
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The roots of a cubic |
2010-01-21 |
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Laura pose la question :
Consider the equation x^3 + 6x^2 - x = 30.
One of the roots is equal to the sum of the other two roots.
Find the values of the three roots.
Chris Fisher and Harley Weston lui répond. |
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The inradius of an icosahedron |
2010-01-21 |
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fnavroth pose la question :
Suppose you have an equilateral triangle.
The area of the triangle is exactly 1200 square centimetres.
Now suppose you have twenty of those triangles.
It's possible to assemble those twenty triangles into a closed
three-dimensional shape, a regular polyhedron.
What would be the volume, in cubic centimetres, of the largest sphere
that could fit inside the shape?
Chris Fisher lui répond. |
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A trig identity |
2010-01-21 |
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Alesia pose la question :
How to prove Csc(A+B) = (csc A Csc B)/ (Cot A+ Cot B)
Penny Nom lui répond. |
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The cube of an integer |
2010-01-20 |
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Shankar pose la question :
Can the cube of an integer end with 1985 ones ?
Robert Dawson lui répond. |
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