It’s the end of the year so it’s time for the year-end summary of **Proofs from the Book**. Below are the most popular posts in terms of number of shares.

**Most Shared Post**

- An Intuitive Proof to The Infinitude of Primes

- The Triangle Angle Sum Theorem
- What are mathematical proofs, really?
- The Sum of the Exterior Angles of a Polygon
- The Quadratic Formula Theorem
- A Mathematical Proof that Two Equals One
- The Proof of the Midpoint Formula
- A Proof that Square Root of 2 Plus Square Root of 3 is Irrational
- The Exterior Angle Theorem
- Reversing the Inequality Sign

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