Pentagons and the Golden Ratio

Additional information

Continuing on from Zvezda's previous video about Ptolemey's Theorem (see: https://youtu.be/bJOuzqu3MUQ) now we use it to prove some cool stuff with pentagons and equilateral triangles.

Zvezda's Numberphile playlist: http://bit.ly/zvezda_videos

Zvezda's webpage: https://math.berkeley.edu/~stankova/

Golden Ratio: https://youtu.be/sj8Sg8qnjOg

Epic Circles: https://youtu.be/sG_6nlMZ8f4

Triangle Magic Highway: https://youtu.be/wVH4MS6v23U