👉 Learn how to prove that two triangles are congruent. Two or more triangles are said to be congruent if they have the same shape and size. There are many postulates and theorems to determine whether ...

I first started teaching Geometry last year and have taken over "Informal Geometry" this year. As the name of the second class implies, the idea of formal proof is strongly de-emphasized; this class ...

Two years ago, a couple of high school classmates each composed a mathematical marvel, a trigonometric proof of the Pythagorean theorem. Now, they’re unveiling 10 more. For over 2,000 years, such ...