Convex

The video tutorial discusses the boundary of a circle and the historical use of convex lenses. Convex lenses have been utilized for vision correction, magnifying objects, and as burning glasses for approximately 3000 years.

What is the significance of the boundary of a circle in geometry?

How have convex lenses been utilized in vision correction?

What are some historical uses of convex lenses beyond vision correction?

Discuss the role of burning glasses in ancient practices.

In what ways have lenses evolved over the past 3000 years?