8a, Arc length and Area of Sector of a circle

Proof of an arc length of a circle, Proof of an area of a sector of a circle, ⭐️Please subscribe for more math content! ☀️support bprp on Patreon: https://www.patreon.com/blackpenredpen Guess what my first job was! https://youtu.be/RSCzXXeqGbU , My simple setup: ? https://youtu.be/IKk7k-CMttE , Check out my site & social media ? https://blackpenredpen.com ? https://twitter.com/blackpenredpen ? https://www.instagram.com/blackpenredpen/ Thank you for supporting! You're awesome and I know it! blackpenredpen | 曹老師