shoutout:

- https://www.mathsisfun.com/geometry/interior-angles-polygons.html
- https://educationisaround.com/sohcahtoa/
- right triangle with two equal sides: http://www.math.com/school/subject3/lessons/S3U3L4DP.html#:~:text=A%20right%20triangle%20can%20also,that%20is%20an%20isosceles%20triangle.
- bounding box of ngon: http://calcresource.com/geom-ngon.html
- law of cosines: https://courses.lumenlearning.com/suny-osalgebratrig/chapter/non-right-triangles-law-of-cosines/

The Law of Cosines states that the square of any side of a triangle is equal to the sum of the squares of the other two sides minus twice the product of the other two sides and the cosine of the included angle.