Lesson 1.2.4: Unknown Angle Proofs (Writing proofs) |
For this lesson there are 11 steps for you to take. Scroll down and do each step one-by-one. The instructions under each step will help clarify exactly what you need to do, so please read all the instructions.
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Here is the worksheet for Lesson 1.2.4
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1.) Video: Start your notes
Watch the video and take ALL the notes. |
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2.) Read more deductive reasoning examples
Here is a list of some deductive arguments. Read at least a couple to get a better idea of what deductive reasoning is. Read them all if you so choose.
Here is a list of some deductive arguments. Read at least a couple to get a better idea of what deductive reasoning is. Read them all if you so choose.
- In mathematics, If A = B and B = C, then A = C.
- All apples are fruits, all fruits grow on trees; therefore, all apples grow on trees.
- William is a bachelor, all bachelors are single; hence William is single.
- All dolphins are mammals, all mammals have kidneys; therefore all dolphins have kidneys.
- Since all squares are rectangles, and all rectangles have four sides, so all squares have four sides.
- If Dennis misses work and at work there is a party, then Dennis will miss the party.
- All numbers ending in 0 or 5 are divisible by 5. The number 35 ends with a 5, so it is divisible by 5.
- The Earth is a planet, and all planets orbit a sun, therefore the Earth orbits a sun.
- It is dangerous to drive on icy streets. The streets are icy now so it is dangerous to drive now.
- All cats have a keen sense of smell. Fluffy is a cat, so Fluffy has a keen sense of smell.
- The elm is a tree and all trees have bark, so elms have bark.
- Snakes are reptiles and reptiles are cold-blooded; therefore, snakes are cold-blooded.
- Cacti are plants and all plants perform photosynthesis; therefore, cacti perform photosynthesis.
- Red meat has iron in it and beef is red meat, so beef has iron in it.
- Acute angles are less than 90 degrees and this angle is 40 degrees so this angle is acute.
- All noble gases are stable and helium is a noble gas, so helium is stable.
- Elephants have cells in their bodies and all cells have DNA, so elephants have DNA.
- All cars have at least two doors and a Ford Focus is a car, so the Ford Focus has at least two doors.
- All horses have manes and the Arabian is a horse; therefore Arabians have manes.
3.) Video: Sherlock Holmes Showing off Deductive Reasoning
Watch this video to see deductive reasoning in action. |
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4.) Video: Writing a Proof
This video will walk you step by step through a proof. It is a long video, but please watch the entire thing. Feel free to put it on 1.5 speed if you feel like you can understand what I am saying. And definitely write everything down that I write down. Writing proofs can be a difficult thing, so listen closely to my advice as I work through this proof. |
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6.) 6.) Video: Solving the proof
Watch me solve the proof you just attempted. |
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8.) Video: Solving the proof
Watch me solve the proof you just attempted. |
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