# Parabola

A parabola is a type of conic section. It can be described algebraically by an equation of the form $y=ax^2+bx+c$ ($a$, $b$, $c$ constants, $a$ nonzero).

The path of a thrown object is a parabola.

A parabola has an axis (the line of symmetry of the curve) and a focus on the axis. For the parabola with equation $y=x^2/4a$, its axis is $x=0$ and its focus is at $(0,a)$.

Light travelling towards a parabolic mirror parallel to its axis will be reflected to pass through the focus.