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How many socks make a pair?

This teacher package brings together our material on trigonometry, from problems about simple triangles to the wavy behaviour of trig functions.

Helen Joyce is a former editor of Plus magazine who now works as a journalist for The Economist. In August she's off to Brazil to be the paper's Brazil Bureau Chief. In between packing and learning Portuguese she has found time to tell Plus all about her varied career and the role maths has played in it.

Comparing and communicating small lethal risks is a tricky business, yet this is what many of us are faced with in our daily lives. One way of measuring these risks is to use a quantity called the micromort. David Spiegelhalter and Mike Pearson investigate.

When you flip a coin we assume it has equal chance of coming up head or tails, so any coin flipping game should be a fair one. But Yutaka Nishiyama and Steve Humble can give you the winning advantage.

Fractals are a treat for your eyes, but what about your ears? Dmitry Kormann, a composer/keyboardist from São Paulo, Brazil, explains how he integrates fractal-like patterns in the very structure of his music, to obtain beautiful results.

"It's a match!" cries the CSI. At first glance it might seem that if the police have matched a suspect's DNA to evidence from the crime scene, then the case is closed. But some statistical thinking is required to understand exactly what a match is, and importantly, how juries should assess this as part of the evidence in a trial.

The human genome is represented by a sequence of 3 billion As, Cs, Gs, and Ts. With such large numbers, sequencing the entire genome of a complex organism isn't just a challenge in biochemistry. It's a logistical nightmare, which can only be solved with clever algorithms.

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Martino Barenco and Mike Hubank shed light on suicidal cells and a mathematical model that could help fight cancer.