From a point `(sintheta,costheta)`, if three normals can be drawn to the parabola `y^(2)=4ax` then the value of a is

From a point (sintheta,costheta) , if three normals can be drawn to the parabola y^(2)=4ax then find the value of a .

Three normals drawn from a point (hk) to parabola y^(2)=4ax

From a point (h,k) three normals are drawn to the parabola y^2=4ax . Tangents are drawn to the parabola at the of the normals to form a triangle. The Centroid of G of triangle is

From a point (h,k) three normals are drawn to the parabola y^2=4ax . Tangents are drawn to the parabola at the of the normals to form a triangle. The centroid G of triangle is