Due to your previous 2 videos I was able to do the both questions with almost same approach as yours (but didn't thought about second answer in Q2). Thanks for uploading such kind of videos ❤.
I have solved these question previously.. but my solutions were 2-3 lines longer than yours.. i was dead set on using cyclic quadrilateral properties in the first one😅.. sir your methods of solving are beautiful
A-Ic is normal to va and B-IC is normal to vb. In prob va and vb are given to be perpendicular to each other. So their normals will also be perpendicular.