Question

In the given figure PQ || BA and PR||CA. If PD = 12 cm find BD×CD.

Answer 1

Could this help you?

Answer 2

In triangle DPR ,

CQ || PR

Therefore, DC/CP =DQ/QR —(1) |By thalus theorum|

In triangle DBR

PQ || BR

DP/PB =DQ/DR —(2) |By thalus theorum|

From (1) and (2),

⇒DC/CP = DP/PB

⇒DC.PB = CP.DP

⇒DC( BD-PD )=(PD-CD) DP

⇒DC(BD-12 ) = (12-CD ) 12

⇒DC.BD-12DC = 144-12CD

⇒DC.BD = 144

⇒BD.CD = 144

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