Two identical triangles, but one with hole

I couldn't believe my eyes. Couldn't see how's that possible. Thought for a while. Gave up and constructed them with Excel:

What I saw was this post from Quora Digest, one of 16 answers under: What are some iconic mathematical images?

In one of my posts I recalled seeing a picture of the famous Russian mathematician Andrei Kolmogorov teaching primary class in a Time-Life paperback I once had. Below is the picture appearing at the top of the Quora answer: Pál Erdős explaining a problem involving some sequence of integers and a squarefree number n to a 10 year-old Terence Tao at the University of Adelaide in 1985. Couldn't help being nostalgic imagining myself in the boy's place.

Well, some are luckier than others. But not Ramanujan. And he didn't need any tutoring in math; but badly needed advice on how to take care of his health!

I had always loved this picture of the prince of the autodidacts and genius. But only now could I see he's doing math in his head while sitting for the photo! Thanks Quora User who posted it.

Then I was thrilled to see a sample of what Everiste Galois has scribbled on the night before his fateful duel the next day. He was my mathematical hero, not because I know his great contributions: group theory and Galois theory, but because he was a brilliant mathematician who died so young and foolishly at 20.

Quora, the source for these posts was co-founded by two former Facebook employees, Adam D'Angelo and Charlie Cheever. It's a nice question-answer site. I've subscribed to the Quora Digest, and regularly received the digest through email. Many people, including my son has half-forgotten the email (old fashioned?), since they are happy working with social media. So it's refreshing to receive social media through email; a little twist.