Full disclosure: I received a free copy of the book on the promise that I would write this review, but you have my word that what follows is my honest appraisal! I need to take this opportunity to apologise profusely to Matt[1].
Love Triangle[2] is Matt Parker's nth offering to the pop-sci shelves in your bookshop of choice, where n is a number that's a little bigger every time I look it up. He's one of the more well-known current writers of books destined for that section that have an explicit focus on maths, and his trademark informal style of unashamed explicit nerdity carried along by a current of comic sarcasm might not be for everyone, but it does seem to do the job for more people than it doesn't.
My copy of the book starts with a note...
To Thomas,Hope you lovethis book aboutloving triangles.
... and I have to say at the outset that I do.
Its subtitle, The Life-Changing Magic of Trigonometry, reassures us that this book isn't a foray into romantic fiction. Instead, it's very much romantic fact: Matt Parker loves triangles, and for very good reason. He begins by introducing us to probably the most famous mathematician to non-mathematicians, Pythagoras, who almost every living Brit has heard of unless they had a highly specific pattern of absences spanning their schooldays. I'm all for exploring the history-of-maths[3], and Parker doesn't disappoint, peppering his introduction with some quickfire examples of triangles being very useful to humans throughout their development.
Chapter 1 focuses on some key properties of triangles that allowed the ancients to get started using them to measure, build and share, prompting the birth of geometry about four thousand years ago. He provides examples of calculations involving triangles that are used to solve problems, end arguments, and while away time on holiday, and then takes us on a chain of events that begins with measuring the length of a stick and ends with calculating the size of one of the biggest things in the universe.
While Parker's prose is, I feel, accessible and entertaining[4] to readers of all self-perceptions regarding ability in maths, he's not one to shy away from including opportunities for his more mathematically excitable audience members to get their nerd on. Anyone who's already experienced some of his other books will have noticed a penchant for using a page numbering system that makes you work to find out what number page you're on. He scratches that particular itch here too, and it took me a few pages to figure out. The theme of the book is a clue, naturally, and I won't spoil things here.
One of the running themes of the book is that everything is triangles and Parker demonstrates this across ten chapters, each beginning with a single idea sparking a stream-of-consciousness power-walk through the triangular landscape, zig-zagging between real-world applications and theoretical and conceptual understanding. Chapter 2 starts with a game of pool, explores how rainbows work, and ends up at the end of the dinosaurs. Chapter 3 explores six laws of triangles, including the famous one that Pythagoras almost certainly did not originate, and one attributed to a mathematician known as Heron. Chapter 4 looks at the various applications that result from approximating complicated surfaces by breaking them down into meshes of triangles, which leads nicely into Chapter 5's rummage through ideas and uses of mathematical tilings and... whatever the 3D version of tilings are called.
Much of this appears to merely be a vehicle for Parker to get from one groan-worthy pun to the next, but far from being a criticism I feel that this smooths the way through a journey which, even if it doesn't involve a swim through the waters of deep and potentially scary maths, at least stops off for a paddle by the shoreline at a number of points.
These early chapters lay down basic ideas of geometry and trigonometry that allow Parker to take us a little deeper into their applications, and he does so partly with reference to theory (I particularly liked his assertion that 'the power of trigonometry is not memorising equations, but rather knowing you can look them up and having faith they will solve all your problems'), but he always supports this with examples, many of which are surprising and lifted from contexts that may initially seem distant from maths including, in Chapter 7, basketball and DOOM (the computer game).
Chapter 8 helps us to explore our place in the world - very literally - and Chapter 9 puts things into perspective, both themes beginning with ancient (chapter 8) and surprisingly recent (chapter 9) historical contexts leading to more modern concerns like GPS, Guns 'n' Roses, impossible footballs, and some groundbreaking CGI scenery that provides a backdrop to the exploits of Matthew McConaughey and Anne Hathaway. Chapter 10 makes waves - sine waves - by mentioning just some of the ways that they contribute to such diverse endeavours as tracking monkeys and detecting collisions between black holes.
Love Triangle: The Life-Changing Magic of Trigonometry[2] is a book that many of those already singing in the maths choir will undoubtedly enjoy, but it could also form a decent entry point for someone less confident in their own mathematical ability but open-minded and wishing to dip a toe into the rivers of mathematics. There are mathsy diagrams from time to time; even the occasional equation, but each is gently explained and clearly related to real-world contexts. It does assume that a reader will have a certain amount of resilience if they run into a topic that might be tricky to absorb first time around, but whenever Matt takes us into a tougher climb, a rest-stop is never far away, and his indefatigable sense of humour is a constant background reminder that it's not a problem if we don't get the hang of everything on the first pass.
My review is done, but I'd like to mention two things that make an appearance in the conclusion to Love Triangle: first was the surprising reference to a topic that has seen me falling down many a late-night rabbit-hole of nerdity: Brian May's guitar. And lastly, that giant of mathematics communication, Adam Atkinson; a reference made poignant by his departure to the Great MathsJam in the Sky just a few short months after publication. There is a page of heartfelt tributes to Adam here: gathering4gardner.org/remembering-adam-atkinson/
Finally, as a treat for anyone who read this far, a single line early in Love Triangle prompted me to create a crossword about triangles. Let me know how you get on!
Footnotes
- This makes it sound like it's a bad review, which is naughty of me, because it very much is not. I'm apologising to Matt because I received my copy of the book before it was published in August 2024 and it's now April 2025. It has been, to say the least a bit of a year. [back]
- If you intend to buy the book I'd recommend finding a local independent bookshop and buying it from them because they need and deserve some support. If, however, you'd rather buy it from Amazon then I'd appreciate it if you did so after clicking this link to get there as I'll get a cut (without increasing the price you'd pay if you didn't click that link to get there). [back]
- And the mathematics-of-history. For many of the historical stories explored in Love Triangle it's difficult to decide which label fits best. [back]
- Not to mention inclusive: it has prompted a small amount of ire (in the form of negative reviews) from the kind of people who like to complain about things being woke, so it's almost worth buying it immediately just to spite them. [back]
