A beluga whale. Photo: Premier.gov.ru, CC BY-SA 4.0.

Whales are under threat from all sides: whaling, the degradation of habitats, toxins in the water, the damaging effects of sonar, and climate change.

There is also the very real danger of being struck by ships. To avoid whales, shipping crews need to know where they are. This is where Pythagoras' ancient theorem about right-angled triangles comes in: a simple application of the theorem can save whales!

To find out more read *Saving whales using Pythagoras*.

*Return to the Plus advent calendar 2019.*