Semi-latus rectum is the harmonic mean of SP and SQ where P and Q are the extrimities of the focal chord

Prove that the semi-latus rectum of the parabola y^2 = 4ax is the harmonic mean between the segments of any focal chord of the parabola.

Prove that the semi-latus rectum of the parabola y^(2) = 4ax is the harmonic mean between the segments of any focal chord of the parabola.

If l denotes the semi-latusrectum of the parabola y^(2)=4ax, and SP and SQ denote the segments of and focal chord PQ, being the focusm the SP, I, SQ are in the relation

If H is the harmonic mean of P and Q, then the value of H/(P)+H/(Q) is

If H is the harmonic mean between P and Q then find the value of H/P+H/Q.

PQ is a normal chord of the parabola y^2= 4ax at P,A being the vertex of the parabola. Through P a line is drawn parallel to AQ meeting the x-axis in R. Then the length of AR is : (A) equal to the length of the latus rectum (B) equal to the focal distance of the point P (C) equal to the twice of the focal distance of the point P (D) equal to the distance of the point P from the directrix.