The triangle shape on sweatshirts and jumpers has become more of a fashion trend in recent years - but it turns out there's a practical reason for the design dating back a century ...

Fashion fans have been left baffled by the inclusion of a triangle shape on many sweatshirts and jumpers, but traditionally, there is a very good reason behind it ...

That tiny triangle on your jumper began as a functional athletic panel but now remains as a classic design feature. It's another of those minor details you've likely spotted before, but never thought ...