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If `P S Q`is a focal chord of the parabola `y^2=8x`such that `S P=6`, then the length of `S Q`is6 (b) 4(c) 3 (d)none of theseA. 6B. 4C. 3D. none of these |
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Answer» Correct Answer - C (3) Since the semi-latus rectum of a parabola is the harmonic mean between the segments of any focal chord of the parabola, SP, 4,SQ are in H.P. Therefore, `4=(2SPxxSQ)/(SP+SQ)` `or4=(2(6)(SQ))/(6+SQ)` `or24+4(SQ)=12(SQ)` `orSQ=3` |
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