Is there something wrong with this solution? Coordinate Proofs.

[mathsaccount]

 

[stapel]

View attachment 37288

Why do you ask? What are you thinking is wrong with the proof?

 

[lookagain]

@ mathsaccount -- Yes, there is!

Starting with the slope of BC, it should be $\displaystyle \ \dfrac{rise}{run} \ = \ \dfrac{0 - y}{-r - x} \ = \ \dfrac{y}{r + x}.$

The same type of error was made with the slope of AC.

The product of the slopes needs to be reworked.

However, in the end, the product of the slopes will still equal -1.

And, the conclusion will still be the same.