The Pythagorean Theorem - Educational Outreach

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The Bride’s Chair and Kurrah’s subsequentdissection has long been the source for a little puzzle thathas found its way into American stores for at least fortyyears. I personally dub this puzzle ‘The Devil’s Teeth’,Figure 2.19. As one can see, it nothing more than theBride’s Chair cut into four pieces, two of which are identicalright triangles. The two remaining pieces are arbitrarily cutfrom the residual of the Bride’s Chair. Figure 2.19 depictstwo distinct versions of ‘The Devil’s Teeth’.Figure 2.19: ‘The Devil’s Teeth’The name ‘Devil’s Teeth’ is obvious: the puzzle is a devilishone to reassemble. If one adds a little mysticism about thesignificance of the number four, you probably got a winneron your hands. In closing, I can imagine Paul Harvey doing aradio spot focusing on Kurrah, the Bride’s Chair, and thethousand-year-old Transformers proof. After thecommercial break, he describes ‘The Devil’s Teeth’ and thesuccessful marketer who started this business out of agarage. “And that is the rest of the story. Good day.”Note: I personally remember this puzzle from the early 1960s.52
2.5) Bhaskara Unleashes the Power of AlgebraWe first met Bhaskara in Chapter 2. He was the 12 thcentury (circa 1115 to 1185) Indian mathematician whodrew the top diagram shown in Figure 2.20 and simplysaid, “Behold!”, completing his proof of the PythagoreanTheorem. However, legend has a way of altering details andfish stories often times get bigger. Today, what is commonlyascribed to Bhaskara’s “Behold!” is nothing more than thenon-annotated square donut in the lower diagram. I, forone, have a very hard time beholding exactly what I amsuppose to behold when viewing the non-annotated squaredonut. Appealing to Paul Harvey’s famous radio format asecond time, perhaps there is more to this story. There is.Bhaskara had at his disposal a well-developed algebraiclanguage, a language that allowed him to capture preciselyvia analytic geometry those truths that descriptive geometryalone could not easily convey.Figure 2.20: Truth Versus Legend53
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The PythagoreanTheoremCrown Jewel o
Page 4: The Pythagorean TheoremCrown Jewel
Page 7 and 8: Table of ContentsList of Tables and
Page 9 and 10: List of Tables and FiguresTablesNum
Page 11 and 12: Figures…continuedNumber and Title
Page 13 and 14: List of Proofs and DevelopmentsSect
Page 15 and 16: PrefaceThe Pythagorean Theorem has
Page 17 and 18: 1 : 2x2x2****22 13x 7 13x 7 0 : a
Page 19 and 20: 1) Consider the Squares“If it was
Page 21 and 22: s090045 0ss45450450090Figure 1.3: O
Page 23 and 24: Notice that the right-triangle prop
Page 25 and 26: The middle square (minus the donut
Page 27 and 28: Our proof in Chapter 1 has been by
Page 29 and 30: 2) Four Thousand Years of Discovery
Page 31 and 32: The proof Pythagoras is thought to
Page 33 and 34: cabcFigure 2.4: Annotated Square wi
Page 35 and 36: Figure 2.6 is the diagram for a sec
Page 37 and 38: 1x:b2:Area(CBA)3:Area( ABC)Area(ABC
Page 39 and 40: Euclid’s proof of the Pythagorean
Page 41 and 42: First we establish that the two tri
Page 43 and 44: 1 2y b b: y b c c2:A3:A4:Aunshaded
Page 45 and 46: XB'A090 CBFigure 2.12: Euclid’s C
Page 47 and 48: 2.3) Liu Hui Packs the SquaresLiu H
Page 49 and 50: One of my favorites was Boxel, a ga
Page 51 and 52: 2.4) Kurrah Transforms the Bride’
Page 53: Note: as is the occasional custom i
Page 57 and 58: 2.6) Leonardo da Vinci’s Magnific
Page 59 and 60: In Figure 2.24, we enlarge Step 5 a
Page 61 and 62: But, this is precisely the nature o
Page 63 and 64: 2.8) Henry Perigal’s TombstoneHen
Page 65 and 66: In the century following Perigal, b
Page 67 and 68: Returning to Henry Perigal, Figure
Page 69 and 70: Figure 2.32 is President Garfield
Page 71 and 72: Even though the Cartesian coordinat
Page 73 and 74: B 2← γ →α y βx C-xC 2Figure
Page 75 and 76: Being polynomial in form, the funct
Page 77 and 78: Thus, the critical point ( C 2 ,0)i
Page 79 and 80: Sincexcpwas chosen on an arbitrary
Page 81 and 82: ∂F/∂x = ∂F/∂y = 0x(C - x) 2
Page 83 and 84: Define a new function21 A2 A3 2xcp
Page 85 and 86: 2.11) Shear, Shape, and AreaOur las
Page 87 and 88: Step 1: Cut the big square into two
Page 89 and 90: In Table 2.3, we briefly summarize
Page 91 and 92: We can formally state this similari
Page 93 and 94: What we will do in Section 3.2 is p
Page 95 and 96: There are three Pythagorean-triple
Page 97 and 98: Thus, if we multiply any given prim
Page 99 and 100: The last equality shows that the in
Page 101 and 102: A Pythagorean Quartet is a set of f
Page 103 and 104: 3.5) Pythagoras and the Three Means
Page 105 and 106:
yxy MHxab2ab2 y x FC y ab2ab 2ab y
Page 107 and 108:
Hero was the founder of the Higher
Page 109 and 110:
5 : Solve for area using the formul
Page 111 and 112:
4 : Construct the parallelogram wit
Page 113 and 114:
We already have introduced Thabit i
Page 115 and 116:
Some historians believe Stewart’s
Page 117 and 118:
In pre-computer days, both all four
Page 119 and 120:
One example of a periodic process i
Page 121 and 122:
The six trigonometric functions are
Page 123 and 124:
The following four relationships ar
Page 125 and 126:
As with any set of identities, the
Page 127 and 128:
Figure 3.17 can be used as a jumpin
Page 129 and 130:
The remaining two pillars are the L
Page 131 and 132:
a2Law of Cosines c2 b2 2bccos()The
Page 133 and 134:
An example of a Diophantine equatio
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However, Euler’s Conjecture did n
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4) Pearls of Fun and WonderPearls o
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We have achieved five-digit accurac
Page 142 and 143:
140212213116)74370116)(74370(370)74
Page 144 and 145:
X X X X O X X O X XO X X O O OO X O
Page 146 and 147:
4.3) Earth, Moon, Sun, and StarsIn
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The four-step solution follows. All
Page 150 and 151:
Figure 4.9 depicts Eratosthenes’
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---High above the earth, we see the
Page 154 and 155:
The commonly accepted value is abou
Page 156 and 157:
1BC : tan( BAC)BABC BAtan(BAC)0BC
Page 158 and 159:
BD ACtan( 21 )Even for the closest
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3w 2h s w 5 s w 0.38196s&5 1s
Page 162 and 163:
Figure 4.16: Triangular Phi---The h
Page 164 and 165:
What remains to be done is to devel
Page 166 and 167:
3 : h32 4 h222 2 24C 2 h33162 2 2
Page 168 and 169:
Epilogue: The Crown and the Jewels
Page 170 and 171:
Not only has it endured, but the Py
Page 172 and 173:
A] Greek AlphabetGREEK LETTERUpper
Page 174 and 175:
C] Geometric FoundationsThe Paralle
Page 176 and 177:
8. Congruent Triangles: Two triangl
Page 178 and 179:
3. Rectangle: A bh : P 2b 2h, b &
Page 180 and 181:
Recreational Mathematics11. Pickove
Page 182 and 183:
GGolden RatioDefined and algebraica
Page 184 and 185:
Puzzles (cont)Pythagorean Magic Squ
Page 186 and 187:
Pythagorean Theorem ProofsAlgebraic
Page 188:
Trigonometry (cont)Eratosthenes mea
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