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Finding the Speed of a Truck |
2008-09-08 |
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From Rita:
A state trooper is hidden 30 feet from a highway. One second after a truck passes, the angle theta between the highway and the line of observation from the patrol car to the truck is measured.
(a) If the angle measures 15 degrees, how fast is the truck traveling? Express the answer in feet per second and miles per hour.
Answered by Janice Cotcher. |
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Pages in a Book |
2008-09-08 |
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From Pandora:
Is there a easier way to explain to my child regarding "pages" problem - like when to add one? when to sub tract one?
John read 46 pages in his new book. If he began reading at the top of page 33, on what page did he finish?
and John needs to do 45 pages of problems in his workbook. He finished this assignment at the the bottom of page 99. On what gate did John begain?
Thank you.
Answered by Walter Whiteley. |
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An associative binary operation |
2008-09-08 |
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From Skye:
Suppose that * is an associative binary operation on a set S. Show that the set H={a E S such that a*x=x*a for all x E S} is closed under *. (We think of H as consisting of all elements of S that commute with every element in S.)
Thanks!
Answered by Harley Weston. |
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An exclusion zone around a triangle |
2008-09-07 |
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From Awrongo:
A long time ago Mr Gibson found an island shaped as a triangle with three straight shores of length 3 km,4 km and 5 km. He declared an 'exclusion zone' around his island and forbade anyone to come within 1 km of his shore. What was the area of his exclusion zone?
Answered by Stephen La Rocque and Penny Nom. |
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1/3(2x-1)=1 |
2008-09-07 |
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From Jen:
1/3(2x-1)=1
Answered by Penny Nom. |
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How far was the ship from the tower at 1:30 p.m? |
2008-09-07 |
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From sam:
A passenger on a ship sailing north at 5.0 mph noticed that at noon a radio tower on land was due east of the ship. At 1:30 p.m., the bearing of the tower from the ship was S35degreesE. How far was the ship from the tower at 1:30 p.m.
Answered by Stephen La Rocque. |
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A security camera |
2008-09-07 |
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From Rita:
A security camera in a neighborhhod carnival is mounted on a wall 9 feet above the floor inside a video gallery. What angle of depression should be used if the camera is to be directed to a spot 6 feet above the floor and 12 feet from the wall?
Answered by Stephen La Rocque and Harley Weston. |
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Mixing watercolour paints |
2008-09-07 |
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From bob:
So, I'm making a chart to help me mix watercolor paints. There are
25 different paints. Each paint will mix with another paint just 1 time.
There is no need to mix red with blue, and then blue with red. Since
the result is the same, we only need 1 combination of the 2 paints.
And there is no need to mix red with red, so we can eliminate 25
combinations of the same paint.
Answered by Penny Nom. |
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What is the bearing to the ship from port? |
2008-09-06 |
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From Rita:
A ship leaves the port of Miami with a bearing of S80degreesE and a speed of 15 knots. After 1 hour, the ship turns 90 degrees toward the south. After 2 hours, maintaining the same speed, what is the bearing to the ship from port?
Answered by Penny Nom. |
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2^x = 1,000,000 |
2008-09-06 |
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From Peter:
How do I solve for "x" in the following equation: "2 to the power of x = 1,000,000" ?
Answered by Penny Nom. |
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A tangent to a circle |
2008-09-06 |
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From Jake:
Find an equation of the line that is tangent to the circle x^2 + y^2 = 3 at the point (1,√2)
Answered by Penny Nom. |
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An array of tulip bulbs |
2008-09-06 |
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From Mary:
My daughter had this problem on one of her tests. She forgot to ask her teacher what she did wrong. I understand she did not answer the question
in full, but what she did answer I feel is right.
Please explain to me
the correct answer. Thank you. Mary
Answered by Harley Weston. |
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Parallel and perpendicular lines |
2008-09-06 |
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From C:
Can you help me determine whether these lines are parallel, perpendicular or neither and why?
Problem 1: y=3x+2
y=1/3x - 4
Problem 2: y=1/3x + 1/2
y=1/3 x -2
Answered by Penny Nom. |
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Simplify ((5/7)/(5/14)) + (3/4) |
2008-09-06 |
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From Emal:
How do you simplify completely: ((5/7)/(5/14)) + (3/4)?
Answered by Penny Nom. |
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Is this operation associative? |
2008-09-06 |
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From Francesca:
Determine whether the binary operation * defined is commutative and whether * is associative
* defined on Z by a*b = a-b\
I understand how to figure out if it's commutative, but I thought for a binary operation to be associative, it had to have at least three elements, so I don't know how to tell if this associative or not.
Answered by Penny Nom and Victoria West. |
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