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ABCD is a trapezium in which AB || CD and P and Q are points on AD and BC respectively, such that PQ || DC. IfPD = 18 cm, BQ = 35 cm and QC = 15 cm, find AD. |
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Answer» CONSTRUCTION: JOIN BD In △ABD, PO∥AB [∵ PQ∥AB ] ⇒ AP DP
= OB DO
[ By basic proportionality theorem ] ------ ( 1 ) ⇒ In △BDC, OQ∥DC [ ∵ PQ∥DC ] QC BQ
= OD OB
[ By basic proportionality theorem ] ⇒ BQ QC
= OB OD
----- ( 2 ) ⇒ AP DP
= BQ QC
[ From ( 1 ) and ( 2 ) ] ⇒ AP 18
= 35 15
∴ AP= 15 18×35
=42 ∴ AD=AP+DP=42+18=60cm |
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