why 360 degrees?
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3D and higher
Browse Middle School Conic Sections/Circles
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Selected answers to common questions:
Circle formulas - area, circumference.
Is a circle a polygon?
Why is a circle 360 degrees?
- Explorations of the Circle [02/09/1999]
What is the definition of a circle? How does it relate to pi? What are
the important parts of a circle?
- Finding a Circle's Area Without Pi [02/24/2001]
How can I find the area of a circle without using pi?
- Finding Miles Per Hour [03/06/2002]
If a wheel is making 64.2 revolutions per minute, how many miles per hour
is it going?
- Finding the Area of a Circle [3/25/1996]
Is there an easy way to do find the area of a circle?
- Finding the Circumference [11/27/1997]
Would you be able to tell me how to work out the circumference of a
- Finding the Table's Diameter [05/05/2001]
A circular table is pushed into the corner of a room so that it touches
both walls. On the edge of the table is a scratch 8" from one wall and 9"
from the other wall. What is the diameter of the table?
- Folding a Circle to Get an Ellipse [01/08/2001]
How can I prove that taking a point on a circle, folding it to an
interior point, and repeating this process creates an envelope of folds
that forms an ellipse?
- Formula for the Area of a Circle [12/17/1998]
The formula, and how it works.
- From Degrees to Radians [09/22/1998]
What are radians? How do you convert degrees to radians?
- History of Circle Area Formula [03/19/2007]
Do we know who figured out that pi*r^2 gives the area of a circle?
- How Did Eratosthenes Measure the Circumference of the Earth? [6/26/1996]
Didn't Eratosthenes measure the lengths of shadows of sticks at different
locations on the same day and time of the year, so he had two right
- Inscribing a Regular Pentagon within a Circle [04/15/1999]
What are the reasons for the steps in inscribing a regular pentagon
within a circle with only the help of a compass and a straightedge?
- Intersection of Circles [10/08/1998]
I do not understand the term intersection in geometry.
- An Introduction to Pi and Its Use in Circle Problems [04/28/2004]
The doctor helps a confused student with circle parts, their relation
to each other, and pi.
- Is a Circle a Polygon? [03/07/1999]
A circle is not a polygon.
- Lateral Surface of a Cone [02/10/1999]
How do you find the formula for the lateral surface of a right cone?
- Measuring the Circumference of the Earth [08/16/1999]
How did Eratosthenes use a mathematical formula to prove the earth is
- Origin of the 360-Degree Circle [11/10/1999]
Did the Babylonians discover the 360-degree circle?
- Perimeter of an Oval [04/08/1999]
What is the perimeter of an oval called?
- Pi and the Area of Circles [05/11/1997]
If pi truly goes on and on forever without repeating, is it impossible to
find the exact area of a circle?
- Placing Coins That Touch [8/7/1996]
How many 20-cent coins can you put around a 20-cent coin so that all of
- Polygons and Circles [4/3/1996]
Is a circle a polygon? Why or why not?
- Polygons, Infinite Sides, and Circles [04/03/1997]
Can a regular polygon with an infinite number of sides be a circle?
- Radians and Degrees [11/21/1994]
Why are radians preferable to degree measures?
- Radius of a Pizza [8/27/1996]
If a pizza has an area of 30 inches, what is its radius?
- Regions, Chords, and Circles [02/05/1998]
A given circle has n chords. Each chord crosses every other chord but no
three meet at the same point. How many individual regions are in the
- The Relation of Perimeter to Area [10/2/1995]
I'm puzzled by the ability of two fences with the same perimeter to have
very different areas inside them. I realize by LxW an 8' x 10' fence will
have more area than a 6' x 12' fence, but WHY? Both fences have 18'
surrounding them but different areas. Also does a circle or a square
conserve more area with identical perimeters?
- Rhumb Lines and Great Circle Routes [09/24/1998]
Can you explain great circles and rhumb lines and how they relate to
shortest distances in geometry?
- Rounding Pi [06/01/1999]
Can you prove that the value of Pi cannot be rounded down to 3.0? Is there an error in the Bible?
- Simple Closed Curve [05/22/2001]
Why is a simple closed curve called just that?
- Square Inscribed in a Circle [09/28/1997]
What percent of the circle is contained within the square?
- Subtend [07/23/1997]
Please give me the definition of the word "Subtends."
- Symmetry Lines [03/30/2000]
How many symmetry lines are in a circle?
- Three Cuts and Seven Pieces [01/18/1999]
Is there any way that you can cut a pie into seven pieces with just three
- Traceable Mathematical Curves [10/27/1997]
Is there any way to tell just by looking if a curve is traceable or not?
Is there some property of a curve that will tell you this? Do curves have
- Tracing an Ellipse [08/17/1997]
How do you form an ellipse using 3 points?
- Uses of Ellipses [04/02/2003]
Where are ellipses found in real life?
- Walking Around the World [08/18/1999]
How much farther does a man's head go than his feet when he walks around
the world? Is this a trick question?
- Ways to Remember the Meaning of Circumference, Radius, Diameter, and Chord [03/18/2004]
If the minute hand touched the edge of the clock, would it be most
like a diameter, radius, circumference, or chord of a circle? I have
a hard time remembering what each of those means.
- What is Circumference? [06/25/2001]
My friend told me it's somewhat like the measurement of the outside of a
circle, but I don't understand that.