Designing an Octagon Hay Feeder

1
Designing an Octagon Hay Feeder
2
Objectives

• The student will
• Translate word phrases sentences into
  expressions and equations
• Solve linear equations (determine angle and
  degree of cut)
• Draw and analyze dimensional figures
• Use tools to construct figures

3
Definitions

• Polygon
• A simple closed curve made up of segments
  (each called a side)
• Complimentary angles
• Two angles whose sum is 90 degrees
• Perpendicular
• Two lines intersecting in a 90 degree angle

4
Definitions (cont.)

• Proportion
• A statement that ratios are equal
• Unit of measure
• Linear feet or inches
• Octagon
• Eight sided polygon
• Pentagon (5 sides) and Hexagon (6 sides)

5
Formula for Interior Angle of a Polygon
Angle (N-2) 180
N (number of sides minus two, multiplied by 180
degrees, then divided by the number of sides) N
number of sides
6
Formula for cut of angle

• Divide the degree of angle by 2
• Subtract the degree from 90
• Ex. Degree of cut 135 2
• 67.5
• 90 - 67.5 22.5

7
Optional Formula for cut of angle

• Shortcut for finding the cut of angle is to use
  180º divided by the number of sides ? (180º ? N)
• Example cut of angle for a pentagon
• 180º ? 5 36º

8
Finding the Length of Side

• To find the length of the sides of an octagon
  feeder is to use the formula 2rTan(180º/N) or
  dTan(180º/N), where r is radius and d is
  diameter.
• Ex. 7 diameter feeder 7Tan(180º/8)
  7Tan(22.5º)
• 7(.4142)
• 2.9 or 2 11