CSI Geometry: Logic & Reasoning Detectives, What’s another month without a series of high profile robberies at the hands of the Mathemagicians? The evil genius terrorist group has pulled off another elaborate crime spree that has left the country of France in disarray. As the Mathemagicians work to build their world conquering device, our investigators are trying to piece together the thefts by an anonymous associate, Quasi Truthful. Cocky as always, the Mathemagicians have left behind a trail of mathematical puzzles and a cryptic text message that must be solved. After solving the puzzles, you can decode the message which will lead to Quasi’s favorite number. So far there are six suspects that police have questioned. It is hoped that someone with relatively strong geometry and reasoning skills can crack the codes that have puzzled the detectives on the case so far. Since you are being brought in as a specialist you have to have definitive proof in order for any arrest to hold up in court. You need to be prepared to state your case and demonstrate your understanding of the following skills that Quasi is known to use in the notes. -

Logic and Conjectures

-

Compound Statements

-

Venn Diagrams

-

Deductive Reasoning

Be sure to include: -

Other examples of the concepts

-

Definitions

-

Any other relevant information.

Keep in mind, the slightest miscalculation or illegible footnote could result in a not guilty verdict. Oh, did I mention that use of a calculator might prematurely set off his world conquering device? Good luck to you, gumshoe. Chief Harris

© 21st Century Math Projects

Who is Quasi Truthful? Name: Marie

Name: Aminata

Occupation: Hairdresser

Occupation: Restaurant Owner

Favorite Number:

-21

Favorite Number: 0

Name: Coco

Name: Jessica

Occupation: Trust Fund Baby

Occupation: Musician

Favorite Number: 97

Favorite Number: 44

Name: Napoleon XI

Name: Napoleon XII

Occupation: Pizzeria Owner

Occupation: Pizza Boy

Favorite Number: 11

Favorite Number: 12

© 21st Century Math Projects

Scene #1

Eiffel Tower –- Paris, France

In the middle of the night, Quasi Truthful helicopter in and stole the top deck to the Eiffel Tower. In its place, investigators found this note.

Bonjour, I’m sure some will be salty that I stole the top of the Eiffel Tower. Others will be salty about this geometric proof. Prepare yourselves for a lot more French style sodium chloride-ness (SALT!) Plug in the correct definitions or properties. (You will use one more than once)

̅̅̅̅ ≅ 𝐹𝐻 ̅̅̅̅ , 𝐵𝐸 ̅̅̅̅ ≅ 𝐷𝐹 ̅̅̅̅ Given: 𝐸𝐺 1.

̅̅̅̅ ̅̅̅̅, ̅̅̅̅ ̅̅̅̅ 𝐸𝐺 ≅ 𝐹𝐻 𝐵𝐸 ≅ 𝐷𝐹

1.

2.

EG = FH, BE = DF

2.

3.

EG + BE = FH + DF

3.

4.

BG = EG + BE, DH = FH + DF

4.

5.

BG = DH

5.

6.

̅̅̅̅ 𝐵𝐺 ≅ ̅̅̅̅ 𝐷𝐻

6.

̅̅̅̅ ≅ 𝐷𝐻 ̅̅̅̅ Prove: 𝐵𝐺

Which one is leftover? This will give you your first clue. Addition Property

f=1

Transitive Property

a=3

Given

c=5

Substitution

r=2

Def. of Congruent Segments

n=4

Segment Addition Postulate

e=6

The leftover…

Scene #2

_______=_______

The Louvre –- Paris, France

Investigators believe that Quasi dug a tunnel into the Louvre and stole the legs from the Venus de Milo.

Someone already stole the arms, so I had to go for the legs. Let’s see what kind of deductive skills you have. The four tourists below went to four different landmarks around France. See if you can figure out who went where with just three clues. CLUE 1: Emma, Felix and Clara visited landmarks where they could go inside a structure. CLUE 2: A man took a picture of a landmark with a glass pyramid. CLUE 3: Nate and Emma visited landmarks outside of Paris.

The first letter of the person’s name who went to the Arc de Triumph is equal to -5.

Clara

Nate

Emma

Felix

Palace of Versailles Dune of Pyla Arc de Triumph Louvre

_______= -5 © 21st Century Math Projects

Scene #3

Les Invalides -- Paris, France

The Museum of French Military History was rocked with cannon fire and Quasi Truthful escaped with two replica guillotines.

I wanted to rob the Bastille, but I found out it was torn to the ground! Saltiness! Anywho, I stumbled into this museum. Great military leaders have to do multiple things correctly at one time. Whoever is truthful for both p and q will lead you to your next clue.

Military Leader

(p) Angle 1 is equal to 35 m∠1 = 5x + 10 m∠2 = 30x – 5

Joan of Arc

Charlemange

Charles de Gauille

m∠1 = 9x + 8 m∠2 = 10x + 115

m∠1 = -2x + 21 m∠2 = 6x + 37

Napoleon

The correct clue…

m∠1 = 7x + 28 m∠2 = 63 – 8x

(q) My statement is always true

If p ⋀ q are true… My Clue for You

If AB = BC then B must be the ̅̅̅̅ . midpoint of 𝐴𝐶

If two congruent angles are supplementary then they are right angles.

Through any two points, there is exactly one line.

If two planes intersect, then their intersection is a point.

_______=_______ © 21st Century Math Projects

Scene #4

Château d'If –- Frioul Archipelago, France

Quasi Truthful sailed over to the famed prison fortress and made off with 16,000 pounds of stone. Carved into a cell, investigators found this note:

I really have ~(enjoyed) spending this time with you. I’m sure you are ~(not salty) by now. I think you have a ~(great) chance of catching me. ~(Good) Luck. Before England stole the idea with Sherlock Holmes, C. Auguste Dupin and Monsieur Lecoq were the first real fiction detectives. They could analyze cases and smell the truth. Can you? Use the statements and find the conjunction or disjunction that is true. (You may need to check your literature book)

p

The Three Musketeers are named Athos, Porthos and Thanos

q

Quasimodo was an underdog halfback on the Notre Dame Football Team

r

The Man in the Iron Mask and the Count of Monte Cristo are brothers

s

Ratatouille was based on a true story

p ⋁ (r ⋁ q)

(q ⋁ s ) ⋀ ~r

Which is true?...

Scene #5

q ⋁ (~p ⋀ ~s)

(~r ⋁ q) ⋀ p

______ = ______

Mirazur –- Menton, France

A discarded supply of mutated oysters were found to be picked out of the trash. While it’s unclear how these oysters may factor into the world conquering device, Quasi Truthful left this note.

While my French is a little rusty, I’m pretty sure they like cheese. After the appetizer and entrée in a classic French meal, there is a course of cheese. 200 customers could choose any combination of three different cheeses. The results can be seen in the Venn diagram.

How many people ate Camembert or Brie de Meaux, but did not eat any Roquefort cheese? The answer will be equal to r.

r =____ © 21st Century Math Projects

Scene #6

Axe Historique -- Paris, France

French police were stunned to find all of the shrubs from the famed Axe Historique line of buildings and monuments were uprooted. Written in sidewalk chalk they found this note. Later, they were sent a cryptic text message.

I might come back to visit France just for kicks! I’ve had to spend so much time stealing stuff, I didn’t get to stop and smell the roses. For the final puzzle… Napoleon made a change to the French flag. Are the blue, white and red equal? Au revoir!

Which proof is correct? Option Un By the definition of midpoint of a segment, AB = BC and BC = CD. By the transitive property, AB = CD. Therefore by the definition of congruence, if segments have the same measure then they are ̅̅̅̅ ≅ 𝐵𝐶 ̅̅̅̅ ≅ congruent. Thus, 𝐴𝐵 ̅̅̅̅ 𝐶𝐷 .

Given: Option Deux ̅̅̅̅ , C is Since B is a midpoint of a B is the midpoint of 𝐴𝐶 segment, by its definition, AB the midpoint of ̅̅̅̅ 𝐵𝐷. = BC and BC = CD. By the Prove: converse of the segment ̅̅̅̅ ≅ 𝐵𝐶 ̅̅̅̅ ≅ 𝐶𝐷 ̅̅̅̅ 𝐴𝐵 addition postulate this means the segments have the same measure. Therefore by the definition of congruence, ̅̅̅̅ ̅̅̅̅ ≅ ̅̅̅̅ 𝐴𝐵 ≅ 𝐵𝐶 𝐶𝐷 .

Which is correct?...

_______=_______

CRYPTIC PUZZLE SOLVER TEXT MESSAGE

Haha. You salty. F – (R + A) (N + C) + E Quasi ~(Truthful) © 21st Century Math Projects