Spherical geometry

Okay kiddo, imagine you are holding a big ball. This ball is called a sphere. Now, let's imagine you live on this ball and everything you see and explore is on this ball. That's what we call the world of spherical geometry.

In this world, there are no straight lines like the ones you see on a piece of paper or on the floor. Instead, they are called great circles. A great circle is the largest possible circle you can draw on a sphere, just like the equator. All other circles are called small circles.

Another cool thing about spherical geometry is that there is no such thing as parallel lines. Every line eventually meets at another point on the sphere. Imagine drawing two lines on a beach ball, they would eventually meet at the opposite side of the ball.

Now, let's talk about angles. In normal geometry, we measure angles in degrees or radians. But in spherical geometry, we measure angles in something called steradians. It's like measuring how much of the ball's surface is covered by the angle.

So kiddo, in simpler terms, spherical geometry is like living in a world where everything is on a giant ball, and everything works a little differently than in the world outside of it. It's a fun way of exploring shapes and space.