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## PowerPoint Slideshow about 'Measuring Distances, Angles and Areas' - ianthe

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Objectives

- Describe the advantages and disadvantages of four methods of measuring distance.
- Use each of the four methods in a simulated survey.
- Determine the area of standard geometric shapes.
- Determine the area of irregularly shaped fields.

Common Units of Distance

- Feet
- Yards
- Rods (16.5-ft.)
- Chain (88-ft.)
- Mile (5280-ft.)
- Meters (.3084-ft.)
- Kilometers (.6214 miles)

Four Methods of Measuring Distance

- Pacing
- Odometer wheel
- Taping
- Stadia Method

Pacing

- Simplest and easiest method of determining distances.
- Requires only one person.
- D = Pace factor x # of paces
- With practice, accuracy of

+ 2% is possible.

- Measures “surface distance.”

Odometer Wheel

- Mechanical device for measuring distance.
- Direct reading or
- Revolution counting
- D = # Rev x Circumference
- Only one person required.
- Accuracy of + 1%.
- Measures “surface distance.”

Determine the distance if the wheel makes 200.5 revolutions.

Stadia Method

- Very quick method of determining distance.
- D = (TSR – BSR) x 100
- More accurate than chaining.
- Requires “leveling equipment.”
- Requires two people.

- What is the distance from the level to the rod in this example?

Taping

- Most accurate method of determining distance.
- Accuracy + .03 %.
- Requires:
- Specialized equipment
- Minimum of two surveyors
- Skill

- Equipment:
- 100-ft. steel tape,
- chaining pins,
- range poles,
- plumb bobs,
- hand level

Additional methods

- Optical range finders
- Electronic distance measurement
- Global Positioning System (GPS) receivers

Determining Land Areas

- Why would you need to be able to determine land areas?
- How is land area typically expressed?

Parallelogram

- Formula
- A (ft2) = B’ x H’
- A (ac) = B’ x H’

43,560

H

B

What is the area (ft2), if the Base = 1200-ft and the Height = 300-ft?

What is the area of the trapezoid below?

700-ft.

375-ft.

300-ft.

Trapezoid- Formula
- A (ft2) = H x [(a+b)/2]

A

H

B

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