The focus is S(6, 0) which lies on x-axis.
The directrix is x + 6 = 0 which is a line parallel to y-axis i.e., perpendicular to x-axis.
∴ The parabola is of the standard form
Also, focus (a, 0) (6, 0) directrix x + a = 0 is x + 6 = 0
a = 6
Hence, the equation of the parabola is
Alternative method:
Let line l be the directrix with equation x + 6 = 0
The focus is S (6, 0). Take a point on the parabola.
From P, draw PM perpendicular on directrix l and join PS. By definition of parabola, PS = PM d = p
Squaring both sides, we get
Hence, the locus of P i.e., the equation of parabola is
An equilateral triangle is inscribed in the parabola , where one vertex is at the vertex of the parabola. Find (a) the length of the side of the triangle, (b) area of triangle ABC.