Homothety

Homothety is a big word that means making things bigger or smaller but keeping the same shape. It's like when you use a magnifying glass to make a picture bigger or a shrink ray to make something smaller, but everything in the picture or object looks the same, just bigger or smaller.

Imagine you have a toy car that you want to make bigger. You can use a homothety to make it bigger by keeping the same shape. You can use a blueprint or scale drawings to make sure that the car stays in proportion when you make it bigger.

On the other hand, if you want to make the toy car smaller, you can also use homothety to do that. You just need to make sure that all the parts of the car get smaller at the same rate, without changing how they look.

Homothety is a very useful tool in many areas, like architecture and engineering, where you need to make things bigger or smaller without changing their shape. It's like magic, but really it's just a math trick that helps us keep things in proportion.