Clever method to solve a tricky geometry problem!

Can you solve this geometry problem? Thanks to Lucas from Brazil for the suggestion! Kangaroo Maths 2020 Proof of inscribed angle theorem Subscribe: Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for sales. (As an Amazon Associate I earn from qualifying purchases.) This has no effect on the price for you. My Books (worldwide links) #worldwide My Books (US links) Mind Your Decisions: Five Book Compilation A collection of 5 books: “The Joy of Game Theory“ rated 4.2/5 stars on 159 reviews “The Irrationality Illusion: How To Make Smart Decision