# mtbos iteachmath math maths edtech geometry proof mathedtech figurethat proofwithoutwords collegemath trigonometry mathed msmath trig geomchat precalc mathchat triangle theorem geometrychat steam nonagon polygon algebra circle tangent

Interesting phenomenon that occurs in any triangle. How can we explain the occurrence of the angle bisector? 🤔 (Source: ) https://t.co/tpusqTwVCB

23 85
2020-03-19

An unusual (not often seen) sufficient condition that guarantees a quadrilateral to be a parallelogram. How to prove? 🤔 Source: . https://t.co/WG1ElKNV2v

8 25
2020-02-15

What does it mean for a polygon to be CONVEX? CONCAVE? Here, a quick class opener using 2 different approaches: https://t.co/3M17XDndq2 Why tell Ss when they can explore themselves and tell us?

18 36
2019-10-31

sin(2v) = 2*sin(v)*cos(v): Dynamic & modifiable illustration using equal areas. For a quick investigation for Ss (w/o ID appearing at the end): https://t.co/hIaGZcseR3.

65 150
2019-09-09

SSS (Side-Side-Side) Congruence Dynamic via Transformational SAS & 1 other theorem. Question: Which one? 🤔 https://t.co/bdKZuzNJXK.

6 10
2019-08-23

Morley's Theorem - Dynamic & modifiable illustrator w/o words: https://t.co/se5j3nEutR. How to prove? 🤔

16 47
2019-05-18

More REGULAR NONAGON wonders (inspired by ). What is the measure of the PINK ANGLE here? For a surprise-cameo-appearance-hint, see https://t.co/PPTBT7rkhB.

7 9
2019-05-15

Sum of Measures of a Polygon's Exterior Angles: Alternate modifiable & dynamic illustrators. Explore here: https://t.co/zXdRkaQEym.

7 17
2019-05-03

Equilateral Triangle to 30-60-90 Triangle (w/o words). resource includes key guiding Qs for Ss: https://t.co/mP2kbI1PJz.

45 97
2019-04-30

Polygon Angle Theorems: N = 3 (triangle) through N = 8 (octagon). Dynamic & modifiable illustrators (w/o words): https://t.co/9rPS0hGhQs. (BGM: ).

48 125
2019-04-29

Looks like -dabbling is starting to grow on me. 🙂 What theorem is being illustrated here? Dynamic & modifiable: https://t.co/2zHDDNMnvW.

2 16
2019-04-19

And an arctan(1) & an arctan(2) & an arctan(1), arctan(2), arctan(3): HAPPY PI DAY!!! 😃 https://t.co/8BatAzK6Uj

2 4
2019-03-14

Any 1 Quadrilateral + Bisectors of its 4 Exterior Angles = 😮? How can we formally prove what is dynamically illustrated here? 🤔 (Source: ). https://t.co/27521S487E.

5 12
2019-02-25

In this incircle + extension animation, what is the measure of the green angle? Why is this ALWAYS the case? 🤔(Source: ) https://t.co/A6rEjBr5pT

3 5
2019-02-06

Carnot's - Case of an OBTUSE Dynamic Illustration without Words. How can we formally prove this phenomenon? 🤔(Source: ). https://t.co/qUDdwQwNTh

8 15
2019-01-31