In this section we will look at a number of properties which are unique to the parabola.
PROPERTY 1
The subnormal is the line joining the point where the normal from any point P on the curve cuts the axis, to the point where a line dropped perpendicular to axis from point P meets the axis. This length is constant for any point P on the curve and is equal to half the latus rectum or double VF.
PROPERTY 2
The vertex can be found by drawing a line from the focus, perpendicular to any tangent to the curve and then dropping a line from this point perpendicular to the axis.(this is the same property dealt with when referring to the auxiliary circle.)
PROPERTY 3
The area enclosed between the curve, the axis, and the ordinate QM =2/3 (area of rectangle QMVL).