See also the
Dr. Math FAQ:
Browse High School Practical Geometry
Stars indicate particularly interesting answers or
good places to begin browsing.
- Radius of an Arch [05/25/1998]
Is there a formula to calculate the radius of a circle given the chord
length and the distance from the centre of the chord to the circle?
- Ratios and Geometry [10/29/1998]
An airplane flying at 33,000 feet has a visibility of 100 miles. What
percent of the total land area to the horizon is visible?
- Ratios, Geometry, Trigonometry [06/10/1999]
A homeschool teacher asks for help with triangles, flagpoles, and
- Rectangle Needed To Make Cone [9/5/1996]
I want to make a lampshade by rolling a piece of paper into a non-closed
- Reflective Properties of a Semicircular Mirror [05/16/2000]
What are the reflective properties of a semicircular mirror? Will a ray
exit a semicircular mirror parallel to its entry line?
- Resolving Pitch and Yaw [02/10/2003]
Is there an equation to find the resultant of pitch and yaw?
- Reuleaux Curve Applications [05/25/2002]
What is the Reuleaux curve used for?
- 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?
- Roof Rafters [02/03/1997]
What is the formula that gives the length of a roof rafter if only the
pitch of the roof is known?
- Rotating a Plane about a Point in Space [07/03/2004]
Discussion of a method of rotating the three points of a right
triangle around a point to align with a given plane in a particular way.
- Scanning for Mountains [06/02/1999]
I am standing on a hill scanning the horizon to see a mountain. How high
must the mountain be for high-tech optical equipment to be any use?
- Segment of an Ellipse [09/06/2001]
We often use horizontal oval tanks for storing drinking water and fuel,
and we would like to be able to calculate the contents.
- Setting Sun [5/19/1995]
A fellow Naval retiree and I have been discussing whether the sun appears
to set faster at the horizon near the equator than it does in the
- Sextant Theorem [05/13/2001]
What mathematical theorem is behind using a sextant, and can it be
- Side Length of Octagon Inscribed in Square [9/11/1996]
I have a piece of square plywood (48" on a side) and I would like to cut
an octagon out of the middle. What is the side length of the octagon?
- Sixteen-sided Window [08/05/1997]
I would like to make a sixteen-sided window for the second floor hallway
of my twin girls' playhouse.
- Sizing a Connector [06/01/2001]
I have to come up with a specific diameter for anywhere from 2 to 91
diameters that are bunched together. The application is round wires.
- Spiral Baffle in a Cylinder [6/24/1996]
We have a cylinder, 48 inches in diameter, to put a spiral baffle
inside... What would the radius be?
- Surveyor's Formula [06/05/1999]
Can you give me a method to calculate the area of an irregular polygon
given all the coordinates of the points?
- Swimming Pool Volume [02/28/2002]
What formula would I use to calculate the volume in gallons of a swimming
pool 135' x 70' with different depths of 3', 5', 8' and 11'?
- Tanker Bearings [06/11/2000]
From ship A, the bearing of an oil tanker is 300 degrees; from ship B,
1000 m due west of A, the bearing of the tanker is 060 degrees. Is the
oil tanker the same distance from A as from B?
- Tape Measure Markings [8/11/1997]
What is the small diamond on all tape measures that occurs every 19.2
- Teaching about Bearings [06/08/2000]
What are bearings? Do you have any ideas on how I can present bearings to
my math class in an interesting fashion?
- Tiling a Floor [06/30/1999]
How many square yards is a 12ft. by 15ft. room? How many 8" x 8" tiles
would you need for a 30 sq. ft. room?
- Tipped and Partially Filled Frustum [12/14/2003]
A vessel in a plant where I work is the frustum of a cone on its side.
A liquid is contained in this section and pours out the end of the
cone section, therefore the liquid only takes up a certain portion of
the cone's volume. How can I compute the volume of the liquid?
- Total Area of Multiple Objects [07/18/2002]
I have 6 windows and want to know the total square feet. Do I compute
the areas separately, or add the dimensions and use those to compute
the area all at once?
- Triangular Garden [03/18/1997]
Find the length of a fence that runs from the right angle to the
hypotenuse and separates the garden into two parts of equal perimeter.
- Truncating a Square to Get an Octagon [10/13/2003]
I want to make an octagon by cutting the corners off of a square.
Where do I make the cuts?
- Using Geometry to Make a Roof [8/30/1995]
I'm not a student but a wood worker with a question on solid geometry. I
want to know how to calculate the angle on the sides of triangles in
order to form a cone shaped (not round but angular) roof.
- Variable Volumes in an Oblate Spheroid [12/21/2002]
We need to know how much water is in the tank at any given time.
- Volume of a Cylindrical Tank [2/3/1995]
I have to keep an inventory of how much is kept in a farm of tanks
outside my school. The tanks are cylindrical, which would be no problem
if they were standing on end...
- Volume of a Pond [2/1/1995]
I need to have a large pond cleaned at my place of employment. The pond
is completely filled with waste material and I would like to know how
many cubic yards are in the pond to remove.
- Volume of Dirt [09/29/1997]
You have a mound of dirt that is 2 meters high with a bottom radius of 1
- Volume of Liquid in a Cylindrical Tank [05/08/2000]
How can I calculate volume of liquid in a cylinder that's not full and
- Volume of Partially Full Cylinder on its Side [12/31/2001]
I am in charge of ordering fuel for our company, and the way the owner
calculates the volume is via a grossly simplified percent full
- Volume of Soil [02/16/1999]
How many cubic feet of soil will be needed to fill a 2x6x4x4' by 8"
trapezoidal garden bed?
- Volume of Water Passing through a Pipe [08/12/1997]
How many gallons of water per minute can a 12" cylinder pipe handle?
- Who uses Ellipses? [12/3/1995]
I need to find out someone (or some occupation) that uses ellipses in
- Will the Tree Hit the House? [05/18/1999]
A tree is leaning at 70 degrees, our house is 66 1/2 feet away, and the
angle from our house to the top of the tree is 40 degrees...
- Wood Flooring [08/09/1997]
Estimating the number of linear feet in 1 sq. ft., making wood flooring
3.25 inches wide, producing 5,000 sq. ft. per day.