If PSQ is a focal chord of the parabola y= 8x such that SP= 6, then the length of SP is

Since the semi-latus rectum of a parabola is the harmonic meanbetween the segments of any focal chord of the parabola, SP,4, SO are in HP. Therefore, 4=2SP×SQSP+SQor  4=2(6)(SQ)6+SQor  24+4(SQ)=12(SQ)or  SQ=3