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Browse High School Practical Geometry

Stars indicate particularly interesting answers or good places to begin browsing.

How Much Carpet is Left? [03/27/1999]
We use rolled carpet in our business and would like to know how much is left on a roll given the remaining diameter...

How Much Material on a Spool? [05/02/2007]
A reel of flat blade has an outer diameter of 1016 mm and an inner diameter of 508 mm. The blade thickness is 20 mm. Could you tell me the length of the blade and show me the formula for working it out?

How Much Material to Purchase? [11/01/1997]
Sanchez warehouse wants to install a 3-foot wide ramp from the level floor to the top of the 4-foot high platform...

Importance of Surface Area [05/26/2001]
Why is surface area so important? What kinds of things depend on surface area?

Indirect Measurements and Hubble's Constant [01/31/2003]
How are indirect measurements used in astronomy? For example, how can scientists tell how far the Earth is from Pluto?

Kitchen Tabletop [11/21/2001]
I need to determine the correct pivot point...

Land Plot Area [08/28/2002]
I have a parcel of land. The surveyor has determined it to be 624,630.88 square ft. and 14.340 acres. The legal description is 15.8 acres. How can I figure out the square footage?

Latitude and Longitude and Daylight Hours [09/21/1998]
Is there a formula for calculating the number of hours of daylight, given the latitude and longitude of a point on the globe?

The Law of Margins [9/2/1996]
How do I figure out the margins of my mat using the Golden Ratio?

Length of a Roll of Carpet [08/21/1997]
How can you determine the length of a roll of carpet without uncoiling it?

Length of Cable on a Reel [05/07/2003]
What is the formula used to determine the length of cable on a reel?

Length of Coiled Belt [04/11/2003]
Working with conveyor belts we use a formula that gives a very close approximation of the length of a coil of belt, but I would like to know why.

Linear and Board Feet [01/04/1999]
Can you explain the terms linear foot and board foot as they are used in the lumber industry?

Liquid in an Elliptical Tank [02/28/1999]
Given any height of liquid, say 3 ft., how can I calculate the volume?

Locating a Ship Using Three Angles [07/07/1999]
A ship's navigator saw landmarks in the distance at points A, B, and C, found angles ASB, BSC and CSA, then located the three points on a map to find the exact position of her ship. How did she do it?

Location of Plane Flying on Great Circle [11/20/2003]
An aircraft flies from 60N 030W to 60N 030W following a great circle. When 025W is passed, what will the plane's latitude be?

Longest Ladder [11/30/2001]
Two hallways, one 8 ft. wide and other 4 ft. wide, meet to form a right angle. What is the longest ladder that can go around the corner where the hallways meet?

Longitude-Latitude Product and Distance [02/14/2001]
Is the difference between the product of the longitude and latitude of one point and that of another point related to the distance between them?

Making a Pool Tarp [9/27/1995]
I'm trying to construct a pool frame out of pvc that will be placed over a pool. We already have the pool tarp, but we need to build something that will shed water so it has to have a slope. PVC only comes in 90 degree and 45 degree angles and straight sections. How do I figure out the maximum height the frame can stick straight up in the air to utilize the tarp?

Making Labels for Cones [06/26/1997]
How do you make a label that will fit on a yogurt container without puckering?

Math and Catapults [04/30/2003]
How do you use math while operating a catapult?

Maximizing the Volume of a Box [06/27/1999]
I have a piece of glass that is 14" by 72". What dimensions would I need to make a glass cage with maximum volume?

Maximizing Volume of a Cereal Box [07/08/1999]
Why are cereal boxes the size they are? Is it just to maximize volume?

Measuring a Cylinder for Out of Round Dimensions [03/23/2005]
If I measure a cylinder for roundness with a standard OD micrometer I find a 0.008' difference at 0 degrees and 90 degrees. If I use a 3 point ('V') micrometer I find a 0.001' difference at the same two positions. Why are they different? Which is better?

Measuring Distances in Space [06/02/2008]
How can we measure the distance from Earth to Mars accurately? Space is infinite--how can you measure something that is always moving?

Meteoric Reprise [10/22/2016]
An adult sees a meteor, and wonders how close it came. With two applications of trigonometry laws, Doctor Rick compiles a table of distances.

Minding the Gaps of Picket Fencing [03/17/2012]
Landscaping a fence leads to fractional pickets and frustration. After diagramming a bird's eye view of a model fence line, Doctor Peterson applies some algebra to the key insight: in a straight run of fencing, the spaces between the pickets outnumber the pickets by one.

Miter Angle of a Pipe [02/10/1999]
Find the miter angle of a pipe of certain shape.

Miter for a Pyramid [07/31/1997]
I want to construct a 4-sided pyramid out of glass for a garden fountain. I need to know the degree of miter to put on the edges of the uprights of the triangles...

Name of Truncated Circle [12/29/2003]
What is the name of a rectangle with two rounded ends, like a circle with top and bottom evenly truncated? For example, an 'oval' racetrack with two straightaways on opposite sides, parallel to each other and both of the same length. I know that's not really an oval, but I'm not sure what else to call it!

New TV, Different Aspect Ratio ... Same Height? [01/04/2010]
"What size HD TV do I buy so that its screen is at least as tall as my old TV's was?" Doctor Rick provides some consumer guidance by calling on the Pythagorean Theorem and television industry aspect ratios; then explains how a trigonometric approach arrived at the same conclusion.

Oil Can Dimensions [12/11/2001]
What are the dimensions of an oil can with a one-liter capacity that uses the least amount of tin?

Optimization [11/26/1996]
To make a funnel, we take a circular piece of metal, cut out a sector, and connect the two radial edges together to make an open cone. What should the angle of the sector be to maximize the volume of the cone?

Painting a Column [07/13/1997]
If I have a column 9.5' long and 8'' in diameter, how do I figure out how much paint I need to cover the outside area?

Parabolas in Everyday Life [05/18/2001]
What types of things have been made using parabola shapes?

Parabolic Equation of an Arch [05/25/1998]
Finding the equation of the parabola in the McDonald's golden arches.

Pattern for Lampshade [02/17/2001]
I would like to know the formula for computing the surface area of a lamp shade so that I can make a pattern from it.

Perimeter of Octagon [04/02/1997]
What is the perimeter of a an octagonal garden with a diameter of six feet?

Pipe Needed for Natural Gas Line [09/03/1997]
Two houses are 130 metres apart at distances of 55 and 105 metres...

Pixels in a Triangle [08/02/1999]
How can I find the number of pixels inside a triangle?

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