What Is the Sum of Interior Angles of a Nonagon?

Geometry is the mathematical science that studies spatial arrangement and shapes using figures and lines. In particular, it focuses on the properties of plane (2-dimensional) shapes like triangles, circles and squares as well as 3-dimensional shapes like cubes, cylinders and cones. One of the biggest topics in geometry is angles. An angle is formed by two lines coming together at a single point called a vertex.