MathDB
Find OP

Source: 1966 AHSME #28

August 31, 2011
AMC

Problem Statement

Five points O,A,B,C,DO,A,B,C,D are taken in order on a straight line with distances OA=aOA=a, OB=bOB=b, OC=cOC=c, and OD=dOD=d. PP is a point on the line between BB and CC and such that AP:PD=BP:PCAP:PD=BP:PC. Then OPOP equals:
(A) b2bcab+cd(B) acbab+cd(C) bd+cab+cd(D) bc+ada+b+c+d(E) acbda+b+c+d\text{(A)}\ \dfrac{b^2-bc}{a-b+c-d} \qquad \text{(B)}\ \dfrac{ac-b}{a-b+c-d} \qquad \text{(C)}\ -\dfrac{bd+c}{a-b+c-d}\qquad\\ \text{(D)}\ \dfrac{bc+ad}{a+b+c+d}\qquad \text{(E)}\ \dfrac{ac-bd}{a+b+c+d} \qquad