The correct option is B 1
Let t1,t2,t3,t4 be the parameter
of the points P,Q,R,S respectively. Then, the coordinates of P,Q,R,S are
(ct1,ct1),(ct2,ct2),(ct3,ct3),(ct4,ct4) respectively.
Now PQ is perpendicular to RS
⇒ct2−ct1ct2−ct1×ct4−ct3ct4−ct3=−1⇒−1t1t2×−1t3t4=−1
⇒t1t2t3t4=−1⋅⋅⋅⋅⋅⋅⋅(i)
∴ Product of the slope of
CP,CQ,CR and CS.
=1t12×1t22×1t32×1t42=1t12t22t32t42=1[using(i)]
Hence, option 'B' is correct.