Why can no two people ever see the same rainbow? What happens when you pull a pop song apart into pure sine waves and play it back on a piano? And what did mathematicians have to do with the great pig stampede of 2012? The answer to each of these questions can be found in the triangle. Stand-up comedian an ex-maths teacher Matt Parker is on a mission to prove why we should all show a lot more love for triangles. To make his point, he uses triangles to create his own digital avatar, survive a harrowing motorcycle ride, cut a sandwich into three equal parts, and measure tall buildings while wearing silly shoes. But soon these hare-brained experiments begin to reveal a genuinely important truth: triangles are the hidden pattern beneath the surface of the contemporary world, used in everything from GPS to CGI via Spotify streaming, the play button and your best mate’s triangle tattoo.