An ode to trigonometry, the most important idea in mathematics and the key concept that enables our modern world, from the internationally bestselling author of Humble Pi Contrary to what your friends may have grumbled in high school math class, trigonometry is perhaps the most essential concept humans have ever devised. The simple yet versatile triangle allows us to map the world, launch ships into space, and send cat gifs. Trigonometry also makes it possible to play the piano so that it sounds like a human voice and was crucial to prosecuting the balloon trip company that caused a pig stampede. In Love Triangle, Matt Parker shares plenty of relevant and irreverent reasons we should all show a lot more love for the triangles in our lives. He tells extraordinary and entertaining stories of mathematicians, philosophers, and engineers--starting with Pythagoras--who dared to take triangles seriously. Humans have been using triangles for thousands of years to measure the earth and build structures. But trigonometry also underpins all modern data technology and is the essential component of GPS--without triangles, we'd still be at the gas station asking for directions. Parker convincingly makes the case that trigonometry is vital, fun, and deeply useful. Its rules are the hidden pattern beneath the surface of just about everything we encounter, and we wouldn't exist without them. Luckily, it's never too late to learn!