Analytical Geometry - Parabola

 
   
     
       

Analytic Geometry – Parabola

       

Equation and Properties of Parabola

       

          A parabola is the set of all points in the plane equidistant from a fixed point called the focus and a fixed straight line called the directrix. The vertex lies midway between the focus and the directrix.        

     
     
       
         

Let AF = p, where p is the parameter of the parabola.

         
1. Standard Equation:
         

            \[             y^2 = 2px             \]             This represents a parabola that opens to the right, with the vertex at the origin.          

         
2. Area of Segment Bounded by a Parabola:
         

            \[             A = \frac{2}{3} l c             \]             where \( l \) is the chord and \( c \) is the distance from the vertex to the chord.          

         
3. Eccentricity of a Parabola:
         

            \[             \varepsilon = \frac{FM}{MK} = 1             \]             Unlike ellipses and hyperbolas, a parabola has an eccentricity of exactly 1.          

         
4. Distance from a Point on Parabola to Focus:
         

            \[             r = x + \frac{p}{2}             \]             where \( x \) is the x-coordinate of the point on the parabola.          

         
            Parabola Formula          
         

Key Properties:

         
               
  • Every parabola is symmetric about its axis (line passing through the vertex and focus).
  •            
  • Vertex is the minimum or maximum point depending on orientation.
  •            
  • Focus lies on the axis of symmetry, and the distance from vertex to focus is \( \frac{p}{2} \).
  •            
  • The directrix is a line perpendicular to the axis, equidistant from the vertex as the focus but in the opposite direction.
  •          
         

Applications:

         
               
  • Used in satellite dishes and parabolic reflectors to focus signals.
  •            
  • Common in physics, especially in projectile motion equations.
  •            
  • Found in engineering designs like suspension bridges, lamp reflectors, and antennas.
  •            
  • Used in optics for focusing light and sound waves.
  •          
       
     
         
 
×

×