In the third century BCE, Apollonius of Perga asked how many circles one could draw that would touch three given circles at exactly one point each. It would take 1,800 years to prove the answer: eight ...
Gear-obsessed editors choose every product we review. We may earn commission if you buy from a link. Why Trust Us? This triangle brain teaser isn’t new—shoutout to Popsugar for unearthing it a couple ...