Q.ABC is a right triangle at B , BP perpendicular to AC , PR perpendicular to BC and PQ perpendicular to AB are drawn . Prove that (i) AQ X PR = PQ2  (ii) PQ X RC = RP2 ?



i In AQP and PQB,PAQ=BPQ           PAQ=90-APQ=BPQAQP=PQB   both equal to 90°Therefore, by A-A similarity AQP~PQBAQPQ=PQBQAQ×BQ=PQ2Now, BQPR is a rectangle,BQ=PRHence, AQ×PR=PQ2ii In PQB and PRC,BPQ=CPB           BPQ=90-BPR=CPRPQB=PRC   both equal to 90°Therefore, by A-A similarity PQB~PRCPQPR=QBRCPQ×RC=PR×QBNow, BQPR is a rectangle,BQ=PRHence, PQ×RC=PR2
 

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