Love Triangle - Matt Parker ****

There's no doubt that Matt Parker can make practically anything interesting - this is one of the few books I've ever read where I genuinely enjoyed the introduction. But there was a real challenge here. In a review of a recent book about maps and mathematics I said 'I always found [geometry and trigonometry] the most tedious aspect of maths.' Take a look at the subtitle here: 'the life-changing magic of trigonometry'.

It's no surprise that the 'trig' word turns up - it literally means triangle measuring (trigon is an obsolete term for a triangle). But it inevitably raises a shudder for many. Parker does acknowledge this in his pure trigonometry section, suggesting it's primarily because it's a pain remembering what tan and cos and sin refer to, but pointing out convincingly how useful and powerful trigonometry is. I confess, however, it was still my least-favourite chapter in the book.

Thankfully there's a lot more, introduced with Parker's bubbly brand of humour. If you've ever seen him on stage, he writes as he performs - everything is handled in a light, energetic, slightly gawky way. Occasionally his word-play gets a touch irritating, but maybe that's just me. That doesn't get in the way of his ability to make maths more interesting. When, for instance, he's talking about the non-intuitive Heron's formula that gives the area of a triangle from the lengths of its sides he notes that it 'makes me irrationally angry', which somehow makes it more approachable.

The book goes into triangles in a huge range of applications and oddities, ranging from the balloon and pigs story featured on the cover to how to cut a sandwich into three pieces equal in area and with an equal amount of crust, or to the many engineering and architectural uses of triangles - we are taken into the constant tension between the architect who wants an outcome and the engineer having to make the outcome feasible... often using triangles. They aren't usually alone in such circumstances. We get meshes of triangles and 3D shapes incorporating triangles (and, to be fair, one or two other shapes). We get triangle-related art effects and Fourier transforms. It's triangle heaven.

For much of the time this is an extremely enjoyable read, but sometimes it does suffer from Parker's over-enthusiasm. There is a big difference between being interested in a subject and being obsessed with it. Readers are likely to fit in the first camp, while Parker is unashamedly living in the second. This produces that engaging enthusiasm, but it also means that at times Parker can spend too many words on a topic, leaving the reader thinking 'time to move on'. This is perhaps most obvious in the chapter on different (often weird) shaped solids, but comes up regularly. I didn't find this a big problem, but it keeps the book from perfection.

If you are interested in maths, and particularly if (like me) you are interested in maths but are no enthusiast for geometry and trig, be prepared for pleasant surprises: this is an excellent addition to your shelves.

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Review by Brian Clegg - See all Brian's online articles or subscribe to a weekly email free here